If you always had a problem color between the line you might not want to try it. No really it's not that hard. Just get the tip to dampen with paint and go over with light touch. Don't depress the tip while going over the raised area. You will be a master before you know it.
couldn't use flash,sorry.
I dab a little bit on a nice pointy round toothpick, wipe some off so there is no pooling of paint in the lettering voids, then slowly "drag" the paint over the raised lettering. You need the patience of Jobe no matter how you do this. Slow and steady is the name of the game here.