Taking inspiration from your classical style, my new buddy Merlot and I just finished a female portrait in gouache. I like to think it turned out great, for a dabbler. It will be my next post.
I'm in my sixties and only started painting 3 years ago, after a lifetime w/o art because my art teacher way back when beat it in me that I was no good at it. So I never tried, until my wife started messing around with her art and the supplies were in the house anyway.
Since then, I'm practicing this and that, with miscellaneous media, trying to learn and find out what I actually like. Currently, I'm leaning towards gouache again, on account of the forced spontaneity. So we'll see how it works out. So far, I'm encouraged.
Age doesn't come into this.
Experimenting is a great teacher, but the greatest teacher is your own mistakes.
I advocate the three P's to advance with your artwork.
Practice, Practice, Practice
But put the practice in on the things you are NOT good at and constantly revise that.
You'll get there if you persist.
I'm a bit late, but I'll check out your profile for gouaches.