SEM Interior Paint Question?

I have painted some pieces with success and some without here is my tips.

First wash everything with a scub brush and clothes washing liquid or dry soap in water.
this will clean the pieces and dry them out, i mean the plastic will look clean an moisture starved.
Then Clean everything again b/c once you think its clean it probably needs more.
Then I set everything up for paint and use a rubbing alchoal or mineral spirits to do a final wipe down and tack cloth.
Then I use the adhesion promoter 3 coats of that, followed by 3 coats of the inerior paint. Then let it sit for a day or two.


Now on the pieces that IM painting for my t top I was thinking of using a clear coat over the peices but I havn't decied yet I have a test panel in the garage to see how it looks