I could list articles to read, books to read, exercises to do. But none of that is a good replacement for honest instruction and coaching.
Buy or borrow an inexpensive 22 such as a Marlin 925 or Savage MkII (bolt action), Marlin 795 or Ruger 10/22 (semi auto) and put a cheap 4x scope on top. Buy a couple spare magazines. Buy a cotton web GI sling.
Find the nearest Appleseed even to you, pay your money, and get a good indoctrination into 3 position shooting.