One thing that I like to use.
Jig paint. You can find it at any fishing gear store.
The stuff is tough as nails, most gun solvents wont touch it and a $1.99 bottle will last you almost forever.
Degrease well and just a touch on a toothpick. It flows really well and if you booger any, just use a Q-tip with a touch of enamel reducer on it to clean it up. (Enamel reducer will remove it when it is dry BTW)
I put it on all of my front sights on my handguns. It really helps the sight picture.