If you are in Rio de Janeiro and want to visit the island of Ilha Grande, you can get there by a local bus combined with a public ferry or take a daily transfer from Rio.
The main settlement on the island is called Vila do Abraão and most transport goes to there. There are three main ports on the mainland from where boats regularly leave for Abraão, from north to south: Mangaratiba (closest to Rio), Concecao de Jacarai (the one closest to the island and with most connections) and Angra dos Reis (closest to Sao Paulo). There are slow boats operated by CCR Barcas  with a capacity of 500+ passengers that cost R$15 (prices in this paragraph as per Feb 2016) and they usually leave once a day from Mangaratiba (8am) and Angra (3:30pm) - check their website for the latest timetable. There are also more frequent fast boats for 15-30 people that cost around R$30 (from Jacarei) and there are taxi boats that cost more. This website has some timetables (all in Portuguese but easy to understand with google translate).
To get from Rio to Mangaratiba/Jacarei/Angra you can take the expensive Costa Verde  buses from the Rodoviaria in Rio. It costs R$37.50 to Mangaratiba and R$54 to Jacarei/Angra. You can also get to either port by changing between three or four public buses for less than R$20 but you need to figure out the connections (basically from Itaguai there is a public bus for R$3.60 that goes to Jacarai). Daily buses from São Paulo to Angra dos Reis are operated by Reunidas Paulista .
There are also some tour companies and hostels that sell a door-to-island package for a van and boat. These cost R$100++ one way and they pick up from locations in the touristic parts of Rio.
Perhaps the best way to get to the island from Rio is to take the 05:00 Costa Verde bus to Mangaratiba (R$37.50 as of May 2016), it will leave you at the dock a little past 07:00 so you'll have time to have breakfast and take the 08:00 Barca to Ilha Grande (R$15). You can buy the tickets for the boat right there in a booth, it won't be full because it has a 1,000 passenger capacity. It is also possible to overnight in Mangaratiba, although options are limited - there are no hostels, only a couple of pousadas and a hotel.
From the bus terminal in Angra dos Reis you can take a taxi or walk to the port, is very close and relatively safe. Boats leave from here on a semi-regular schedule. Bus fare to Angra from Rio with Costa Verde (as of May 2016) is R$54. Daily buses from São Paulo to Angra dos Reis are operated by Reunidas Paulista .
Conceição de Jacareí is a district of Mangaratiba - this is the shortest crossing point. Barcas SA also operates this route once a day, weekday departure is at 15:30, at weekends and on holidays it leaves at 13:30. There are also many other smaller boats which make the trip at various times or when they have sufficient passengers.
From Rio de Janeiro, you can now book online for door to island transfers with the Green Toad  or Easy Transfer . Pick-up from your hostel then a 3 hours drive to the docks where the transfer to a boat to travel 30 minutes to the island. You stop at an ATM to cash-up before hitting the island.
It is important to note is that there are no banks on the island, you should bring plenty of cash since not all hotels, shops and restaurants accept credit cards.
Walking on Ilha Grande is not suitable for baggage on wheels due to the sandy trails, but there are porters with push-carts you can hire to help you carry your bags, and following them also helps you find your accommodation.
There are no roads and no private cars on the island. A good option is to use Vila do Abraão as a base and plan day trips from there. There are several hiking trails to the many beaches on the island. Some trails can be strenuous in the tropical weather, so be prepared and take plenty of fluid. Remember that night falls early and dawn is short near the equator, so carry a flashlight if you plan to return after 6PM. Many beaches can be reached by boat and several agencies in Vila do Abraão sell packages for the numerous schooners serving the island. It is easy to find one-way trips and pick ups back to Vila do Abraão on many beaches in the evening.
It is possible to walk around the outside of the island in about 4 or 5 days if you're not in too much of a hurry. Its best to start at Abraão and go in an counter-clockwise direction, through Dois Rios. Note that accommodation on the back side of the island is scarce and free camping is illegal. At Parnaioca beach on the backside, arguably one of the most beautiful spots on the whole island and worth spending at least a couple of days at, you can ask for accommodation in the local houses (there are only about 8 people living there); ask for Sr. João, he'll help you out. Meals can also be purchased, but variety is very limited, so it might be a good idea to take some food. There used to be a camping ground there with some very limited infrastructure run by the locals, but in 2006 that was prohibited by the national environmental agency (IBAMA), and was still prohibited at the end of 2007, although the locals were apparently appealing this ruling.
There are beautiful beaches, some considered to be among the nicest of Brazil.
Lopes Mendes beach was once voted one of the top 10 most beautiful in the world by Vogue Magazine. The sand is very fine and white, and the water is shallow a long way out, making for good surfing conditions - although sometimes the waves close out very quickly. Boats leave Abraão and drop you in Pouso, from here Lopes Mendes is about 20minutes walk on a jungle path to get you nice and ready for a dip. Beware of strong currents and observe the lifeguard's red flag areas. Speedboats charge R$25+ each way, but there are also slower (45minutes), larger boats (50+ passengers), for R$15. It is also possible to hike to Lopes Mendes from Abraão, the trail starts at the end of the main beach. It is over 7km long and takes approximately 3hours - there are some steep inclines and declines.
Parnaioca best beach but only by boat or 3 hour hike from Dois Rios. Two Campings. 
Praia do Leste closed as natural reserve! 
Praia do Sul closed as natural reserve! 
Praia Dois Rios well marked easy hike from Vila Abraão 
Caxadaço well marked hike from Vila Abraão, at the end not easy 
Praia Santo Antonio Quiete alternative with same boat as Lopes Mendes 
Paria Recifes 
Praia do Aventureiro the postcard beach! 
- Hike in the rainforest to Papagaio Peak, at 980+m the 2nd-highest point on the island. It is the pointed peak you will see towering above Abraão, so called because from certain angles it resembles a parrot's head and beak. It is a 2-3hour hike to the top, the trail is marked - despite some warnings you may hear - (no need for a guide) and with a beautiful view from the top, a huge granite rock. Bring lots of water. There is also a company offering a sunrise tour, you start at 2am.
- Cachoeira da Feiticeira is a beautiful waterfall located about 4km from Abraão. The trail begins at the end of the beach (left hand side if you are facing the sea) and is well signposted. You can continue on to a number of beaches, from where you can take a boat back.
- The 7km trail to Lopes Mendes starts at the other end of the main beach in Abraão, near Che Lagarto.
There are a few souvenir shops in Vila do Abraão selling t-shirts, magnets and other stuff. In fact, there is nothing typical or special to buy in Ilha Grande.
There are about 30 restaurants in the island. Some are expensive but there are many cheaper options like hamburgers. Try FOOD for KILO; pay about US $0.80 per 100g for very nice food.
The seafood is generally very good and could perhaps be regarded as a specialty. Many restaurants offer casseroles with several types of seafood, served as a dish for two. Although in the higher price range for Ilha Grande, they are delicious and good value for money. The best place to go for traditional Brazilian is Frutos do Mar located on Rue da Praia. Try their Brazilian fish stew, that alone is worth the journey to Ilha Grande.
It is difficult to find any meal for less than R$20, so consider cooking your own food at your hostel if you are on a budget.
There is no clubbing scene or electronic dance - at night it's drinking beer in the main square and dancing with live local music like bossa nova, forró, and samba. One recent and popular bar is the Cafe Do Mar , which is on the eastern side of Villa do Abraao. Right next to the beach, they serve cold beer, mean caipirinhas and cool music, in a very chilled out atmosphere. They also have well attended BBQ nights, which offer delicious fresh fish etc and serve narghile (also known as sheesha). Kebab is their sister bar in the town itself, offering Greek style kebabs with great juices, drinks and cocktails and the same funky atmosphere. Here there is also a little wok bar where you can see them make noodles for you. Restaurante Esquinas Bar is a good place to sit by the beach. You grab a beer, meet some people, buy some artcrafts and hear the locals play Brazilian music. If it rains, don't worry, it'll pass.
There are plenty of accommodations in Vila Abraão, plus a couple of camping grounds. Free camping is illegal, but you might get away with it on some beaches. You can bring your own hammock. Few campsites have a special place for hammocks (Camping do peixado in Abraao for example).
There are a couple of youth hostels. The best one is a small trek uphill but it is worth passing the first HI and heading up to this one which is in more natural surroundings. Wildlife abundant.
Abraão is basically comprised of two main parallel streets. One goes right by the ocean and the other goes right behind it. As you get off the boat on the pier go to the second street from the ocean and turn left. Most of the budget hostels are on this street. The first you should see is Resta 1. There are also 2 hostels at the end of the beach on the left hand side as you get off the boat. In high season a lot of hostels can be full. Several camping grounds are also available. One which is fairly centrally located and is very likely to have some vacancies is Santana´s Camping. Located on the opposite side to Resta 1 on the street connecting two main streets.
A few inns with standard prices of USD 30-45. All clean and well managed:
Out of Abraão
Aracatiba town is a cheaper option but it doesn't offer much in terms of tourist facilities, it´s more for weekend tourists who live in Angra dos Reis area already. Its location is far away from Abraão, Lopes Mendes or Dois Rios, so it's not a very convenient choice if it's your first visit to the island. Bananal Beach or Sitio Forte have nice mini-resorts, a good option for honeymooners.
In the Blue Lagoon (Lagoa Azul) is a lodge where The Island Experience () is located. This is a 7 day adventure spa which offers trekking, kayaking, yoga, massage and a detox menu. During the Brazillian summer it operates as a pousada under the name Estrela da Ilha ().