what is the best way to clean the internal parts of an air brush, just using it with paint thinner or acholhol or what have you in the bottle?

Here's a thread that was going a few days ago about backflushing the airbrush to clean it internally before changing to the next paint:

https://armorama.kitmaker.net/forums/3683&page=1

The single best way to clean the internal parts of an AB is to take it apart and use a solvent based cleaner if you use solvent based paints, ie: enamals. Use warm water or commercial AB cleaner or somthing like windex if you use water based paints.
You should not have to take it apart everytime you use it, unless of course you use it heavily. The link Tin Can provided to the backflushing method is great if you use it very lightly.

Post back if you need more help.