For general purposes, I use a "daylight" or UV filter on my lenses, mostly to protect the glass. Hoya filters have served me well.
I also have a polarizer for outdoor photography, and a graduated neutral density filter that I seldom play with. The modern digital cameras have a lot of built-in effects that used to be the duty of filters, such as light correction for incandescent and fluorescent bulbs, sepia tones and the like. This is likely a bummer for filter-makers.
I imagine you can get some pretty good info on the web, I did my learning before I was computer-literate. I read a lot of "Outdoor Photography" magazine, filter ads and B&H catalogs to get some info. Scout around using Google and you will get more info than you can absorb, I bet!
Killdeer