I did mine as all the paint on the bottom was coming off. I have a Studio Style Newport 2, and removed and repainted all the markings black, and the sight line back to white. I used a painting needle that you can pick up at hobby shops. The needles give you the ability  to put the paint exactly where you want it and not get it everywhere. After the paint dries, don't rush it, let it sit for a while, you can use acetone to remove any paint that is outside the marks with a little on a rag. Mine turned out good. If you can't find the needles you can use a paint brush, just use a real fine tipped one. Good luck if you decide to go for it.

It's pretty easy to do it.  I used Testors paint and toothpicks.  It just requires a little patience, and some acetone.  Like Alex said, do it color by color and allow the paint to dry before whipping off the excess paint.  There's really no way to mess it up, because you can always start over with more acetone.  

The bottles and needle point tips work well, but clean up is a real chore.  If you've got a steady hand toothpicks are the way to go IMO.

what kind of paint do you recomend

I used Testors model paint. Works very well.  You can pick it up and any hobby shop.

There is a great web site called The Cameron Collector, many posts on differant ways to change paintfill and great pics of color schemes.

I sent mine to scotty to get refurbished. It comes back like a brand new putter. it's well worth it!

My teenage son and his buddies have been doing it with nail polish.