how do you clean a throttle body

First off try pulling the trouble codes from car, as you may have more than just a dirty throttle body going on, in fact it would be atypical for a dirty throttle body alone to prevent a car from starting. You can pick up various cleaners/sprays at any auto parts place. The MAF (mass air flow) sensor should be cleaned ONLY with MAF cleaner, other cleaners will damage it. However, when you first crank an engine, the computer is in "open loop" so most sensor input is ignored until after engine is running, so a dirty sensor in the throttle body shouldn't keep it from starting. Dirty injectors in the other hand, would. Or problems with coils/plugs/timing/injectors. By all means, disassemble the throttle body and clean it, clean all the sensors you can, and clean fuel injectors, give it a tune up, and maybe check the fuel pressure as well. A noid light can also help you check pulse timing on injectors.