bout time you posted a usefull topic

J/K
Here ya go:
The most important part to painting interior trim is preperation. If you don't prepare the surface correctly then you'll get ****py results.
Get some of the following for a auto body supply :
Laqquer thinner (good quality)
Prep- sol solvent
red scotch brite pad
good plastics primer
and a good quality paint
most of these items you can get a Home Depot and an auto parts store with the exeption of the prep-sol in that case just use good rubbing alchol.
1) use thinners to remove the paint from the last attempt
2) wipe with thinners again to clean it again
3) use prep-sol or rubbing alchol and clean the part again.
4) use scuff pad and scuff the entire part really well.
( here's something the looks even better but requires more time. Say you have a part with a texture on it such as a radio and and HVAC control trim panel. Clean it as the instructions above say, then use a peice of 180 grit sand paper and sand the entire part really well then clean the part again. wipe the part with the thinners again and spray some filling primer ( this will require multiple coats to fill in the texture) after you have a good build of primer let it dry for the specific time, then take some black spray paint and dust a little paint on it, (when wet sanding this will show all the low spots and scratches that need more sanding) then using some 400 grit and plenty of water wet sand the part till all the black spray paint is off and you have a nice smooth part.
5) clean part with alchol
6) apply your color
7) apply your clear if needed
8) give yourself a pat on the back for doing such an awesome job!
As always follow the paint manufacture's instructions for using the product.
You should have a very nice upgradded interior trim part after all the work!!
Good Luck!