From Lisbon: take the Rede Expressos bus from the Rede Expressos bus station near the Sete Rios bus station. The nearest station is Jardim Zoológico. It is a little bit difficult to find but if you ask some locals they will get you there easily. Approximately 2 hours to the central bus station in the center of Nazaré. Prices are around 10-11 euros. This is the fastest line.
Trains run the Linha do Oeste line from Oriente station in Lisbon. You have to change and accept lots of stops en route. Arrival will be in Valado dos Frades/Nazare/Alcobaca station, around 5 km. from the center of Nazaré. From there, there´s a local bus going to Nazaré and - normally - it would be possible to get a taxi from the station (normally with a fixed fare).
It´s a holiday town all year around (though some accommodations and restaurants are closed in the winter season). Take pictures of the beach, Sitio; ask the local ladies (who wear seven skirts) if you can take a photo.
There are lots and lots of small cheap restaurants, where they are grilling fish (sardines etc...), chickens outside. Normally it pays off to frequent the smaller streets. On the waterfront and major squares you will find it much more expensive. Lots of nice cafés on the Praça Sousa Oliveira. Not cheap but with a good view of the bustling life.
Arriving at the bus station one will normally be "hijacked" by a group of women who offers private rooms. It´s quite cheap, normally central and the easiest way to get a place to sleep (follow the woman of your choice to see the quarters, but beware - they´re very fast). There are hotels and pensions that can be booked in advance. It´s more (much more) expensive and you won't be able to experience the charm of living in a private home, where the family has moved out (or into one little room) so they can rent the other rooms out.