Ok, so I don't really want to give credit to one person here. If you go to youtube (my favorite place for tutorials!) you will find that many people do this and in many different ways. This is how I do it.
I start with super glue
An empty tea bag,
and a nail buffer.
I cut a small piece of the tea bag to place on top of the crack.
I then place a drop or two of glue on the square and as it dries I tap it down with the end of a paperclip so the edges dry flat to the surface.
It looks real bad, but here it is after it dries:
When it is completely dry, and I mean completely, I start buffing it down. Sometimes I add more than one square, and when I do it's pretty thick. In that case I will start with a course buffer to level it out. But usually a very fine buffer works well. You don't want to thin out your nail so be careful to buff just the glued area.
This is what my final product looks like:
I works for me! I will paint them this weekend and you will see that you can't even tell!
Thanks for checking it out!