For my current contest build, I stripped the paint twice before I got it right.  This happens, and like the others have said, it is how you learn.   The next time you go to build one of these, you won't have this problem.  

Splashcoat is giving you excellent advice on tape.  I have been using tamiya tape for a while now.   Between that and silly putty I have about all the masking options I need.   Masking fluid is nice, but it is hard to find one that works well.   I still haven't found one.