We won't laugh CJ * snicker-snicker *
just kidding.
I use Micro Mask. It's a liquid water soluble mask that I "paint" on to the clear window panes, paint the model and then peel the mask off for nice clean window frames.
Some people use different types of masking tapes by cutting many small pieces and burnishing the edges down to prevent paint runnning under. Some swear by using bare metal foil also.
Also, some people use white glue "elmers" thinned a bit with water as a liquid mask.
Hope it helps,
Eric
Oh, welcome back to modeling and the forum!