You could take a flight from Dushanbe to Khorog. There is a 14 seater flight every morning to Khorog, but its departure depends on weather conditions and the number of passengers. Tickets to the flight are sold a day in advance at the Dushanbe airport.
You could share/hire a jeep from the jeep stand near the airport in Dushanbe to Khorog. This will take between 13 and 21 hours and privately hiring a jeep costs around $400.
From Khorog you can hitch on a fuel tanker or truck on its way back to Kyrgyzstan, or hire your own vehicle from Khorog. Its also possible to get an occasional shared van to Murghab and from there to Osh. Most days will also see a jeep or share taxi head towards Ishkashim. Hitchiking on the Pamir highway requires patience. The first vehicle with space will give you a ride, but as with many places in the former Soviet Union you are expected to pay for the ride. It can take anywhere from 2 hours to 2 days to get a ride. There many only be 2 or 3 vehicles going in your direction each day.
There are no rail or regular bus links in Eastern Tajikistan and, while there are airstrips in a few towns the only one available for commercial use in in Khorog and only flies from there to Dushanbe.
It is possible but difficult to hitchhike on the Pamir highway but if you want to visit anywhere off the road you will need extreme patience or a car. There are a number of drivers who operate in the Pamir region. Costs vary as they all charge for the cost of petrol (variable) plus the accomodation, food and pay of the driver (fixed by driver). PETA or MATT in Murghab and CBT in Osh can arrange drivers but the most cost effective way is to go with a local private driver.
It is becoming more popular to rent an SUV or motorcycle to self-drive the Pamir highway. Most rentals are available in either Osh or Bishkek, Kyrgyzstan rather than in Tajikistan.
Rice, eggs, snacks, yak butter, bread, mutton, Pamiri tea (sheer-chai), freshly made warm bread (non).
Tea, surprisingly good coffee, and vodka. Yak milk.
There are a number of homestays in most villages on the Pamir highway. They are usually in homes built in traditional Pamiri style. They are made with wood, with five pillars, a sky light and richly decorated with carpets. You are ensured great hospitality and simple but delicious meals.
A zealous policeman in Murghab may want to register you with the police or complain if you were taking photos. This isn't a problem, registration should be known well enough simply getting to the area.
There is some risk of altitude sickness.