As far as warpage, that is a hard thing to sometimes deal with. I do have one suggestion that works with some parts. If you paint just half of one side of a part. If you can hang the part, you can paint both sides of one half of a part. Always paint with the grain. Leaving half of the wood unpainted uses the woods strength to keep it from warping. It’s the water and the grain of the wood that usually will make it warp. This is hard to do on tiny parts.
Once the half is dry you can paint the other half. After that sand the piece and it should be sealed. Then you can paint a second coat, usually with no warping.
Many thanks from me and anyone else who finds this. I have added it to the tips section at the top if you need to come back to it some time.