Painting help needed

[Sarge_7]

I picked up an Athearn AC4400CW and a Bachman/Spectrum Dash-8 off of Ebay to restart my model railroading. I haven't painted anything in a long time and think I screwed something up already I am using Badger Model Flex paint for the first time(all that was available to me at the time) I sprayed on a coat of paint that went on ok, but when I went to tape it off for the other color the paint would peel off with the tape. This brings up several questions.
1. What should I be thinning this paint with? or do I need to?
2. Do I need to strip them back down and start over?
3. And what would I use to strip them? Back in the old days we used brake fluid

Thanks for your help.

 

[CN_Fan]

Clean with alcohol then prime it, let dry for a week for the primer to set in. Now paint it. Also, be sure to use GREEN painters trim tape to mask, use nothing else....

 

[MadHatter]

Brake fluid still works fine.