Lol, Mark, you're a smart dad! I wish I had thought of that when my kids were younger.
Megan, there are very few absolutely right and absolutely wrong answers in this asylum known as "hard baits."
But I would suggest that for two or three bucks each, you could buy some unpainted "blank" lures instead of going through the trouble of "roughing up" (meaning lightly sanding) a bait that you bought.
By purchasing inexpensive blanks you will be able to get a good feel for the painting process and if you don't like the results, you can simply wipe off the water-based paints with water and try again. That is a trick we all employ when we make a mistake, even after building for years.
Also the final finished bait will run nicely in the water because you will not be painting over paint, which can at times alter the action a little bit, especially on very small baits. That is a minor consideration, but starting on a clean unpainted bait is just a nice way to go over all.
Vince
fatfingers