Never really worked with the stuff but am looking to paint my badges and chrome trim with it just trying to get an understanding as to how people get such good edges with the names and such. Spanks all =)
Tape off carefully and remove the tape once the final coat is on and still wet. Thin coats built up. You can also use a razor around the edges if it dries or couldn't be taped off
For badges I would just tape a rectangle .5" away from the lettering. Spray light coats like mentioned. When you peel, the edge break between the letter and the car will cause automatic masking and it should peel only the dip around the badge. Window trim can be treated the same but be careful around the window seal.
I'd check out www.dipyourcar.com's youtube page as they have hundreds of videos on techniques.