Not a bad start! I highly advise you to check out some specific miniature paints. The pigments in regular old craft paint are just too big for mini work a lot of the time.

Army Painter makes some relatively cheap sets, you just have to shake the shit out of em before use. Vallejo is another good one!

Have you looked into picking up/mixing a wash or two? I think that could help you advance your skills in a pretty easy way. LukesAPS had a good youtube how-to for mixing your own wash(at least last time i checked he did.) And speaking of thin paint, remember that multiple thinned coats are better than one thick coat.

It sounds like you're rocking some budgethammer(nothing wrong with that, games is games is games) so if mini paints are just a bit of a stretch for the wallet nbd, but at least keep it in mind for when you feel like your skills have plateaued with the materials you've got.

I hope this helps and happy hobbying!