Wanting to repaint the plastics and needing some tips on what guns and brands of paint to buy.

for most plastics, I clean it real good with a mild solvent like alcohol. Next I scuff it real good with a grey scotch pad and spray it lightly with 2 coats of adhesion promoter. Once the adhesion promoter is dry I spray it with 2k urethane primer and finish as you would with metal parts. This has worked well for many plastic parts I have painted but there may be plastics that will lack adhesion no matter what you do.
If the parts are small just about any touch up gun will give you good results. For larger parts the better your gun the better your finish. Use a tip recommended by your paint supplier.

here you go buddy

http://www.bodyshopbusiness.com/painting-plastic/