selling them how? For real money? If so, I'd advise against it (and also for saying 'credit me', since you didn't really create the images). 'Prettying up' a professional artist's work isn't the right thing to do. If it's something like the KAF-bay or whatever it's called, then I suppose that's better. Just don't go making money off someone else's hard work.
The type needs a lot more work, and generally speaking, script fonts are pretty ugly, hard to read, and very hard to use well. These show that, as I really can't read the type of the first sig.
The 2nd is nice, but is the girl a ghost?
The 3rd is nice, but the type is not needed. To have a purple sig, with the word 'purple'...you might as well say "girl with purple hair playing flute"
My point is, you don't really need to reiterate what's happening in the sig. It's a great image though, I just think the type lets it down.
The last one is a little too plain, and looks like an awkward pattern. Again, te type is not really needed. We can see she has a scarf, but the colours just don't connect with it.