I'm a nail polish nut, and there is no such thing as too much glitter for me. (And I'm 47, if that matters.)
Someone else mentioned the accent nail, which is what I was going to suggest. Another option, also mentioned, is glitter toes.
The glitter in those Revlon double ended nail art bottles aren't the easiest glitters to work with. They are a bit chunky, even though they have lovely color.
If you want to ease into glitter, I suggest getting a topcoat with very fine, sparse glitter to start with. Something like Sally Hansen Diamond Strength in Diamonds. Or, if you are feeling braver than that, Glass Slipper, which has some flakey glitter. Both are beautiful, easy to find, and will work with any color basecoat you try.
When you have a little time off, maybe you could experiment with glitter polishes. You may find that after wearing glitter for a while, your eye will adjust to it, and it will seem less childish to you, and just more fun instead.
