Hey Mongoose !
I always paint the vertical surfaces and adjacent parts "Before" sprue removal . This way there's very little if any problems . What I do , and this is a trade secret I now share . When you have all those surfaces painted , get out the X-Acto knife . Fresh Number 11 blade .
Now , using ONLY the KNIFE weight , draw it along the corners between vertical and horizontal surfaces . Now , take Blue Tape , put it on the parts you can do it to , burnish ( rub down ) tightly and spray away .
The little crease you've created with the blade Should prevent paint bleed . Now carefully dry - brush the decks around those vertical surfaces , until they are covered good enough to brush normally .
Brush right up to the little dams and slots and bars they mold to locate stuff . It's very easy to take a little scrape with a number 11 with the end broken off till you have about 1/8 inch straightedge on the end of the blade . Scrape the paint away from those protrusions till you can just barely see model color below .
Put part in place and if possible let the glue ( I use Testor's Regular or Tamiya's ( Green Label ) Liquid glue .Let it run down the inside of the part ( If hollow . ) If solid , use the Tamiya glue and touch the brush tip , full of glue , to one spot on a side that will not be that visible .
If visible then a brush tip with the right color will cover it up ! Good building ... T.B.