First start here:
https://wwwnc.cdc.gov/travel
Some medical clinics will provide immunizations for a fee, which will save you the cost of a "consultation" from the Travel Clinic. I know mine does and my benefits cover it so free vaccines for me!
For most places you'll need to get (or booster):
Typhoid
Hepatitis A/B
DPT
Measles
You might consider:
Yellow Fever (if you're traveling in endemic areas)
Malaria (not a shot, but taken orally during your visit)
Dukoral for Traveller's Diarrhea (also taken orally)
Rabies & Japanese Encephalitis if you're going to be in rural areas for extended time periods.
Good luck!