This is something I have been experimenting with as well.
The pain job depends on the number of colors and how the overall look is going to be.
There are several people here who do well with what your asking.
Here are a few things I found:
if you use shelac make sure the can says wax free.
https://www.youtube.com/watch?v=jKShR3J3VfI
Another clock face - #2 by RobertA_Rieke
Painting a sign? - #4 by RonSwanson