Woodworker here. Havent done much 3D carving or whittling but have done a bunch of letter and relief carving recently. I mostly enjoy making furniture but carving is quick, quiet and i can do it in spurts while the kid and wife are asleep.
My only tip is know what sharp is and know how to get back to it once your knife gets dull. It should be sharp enough to pop individual hairs off your arm. Personally, im a wet stone (220, 400, 1000, 8000g) and leather strop (with yellow flexcut compound) guy.
Look up Mary May or Lora Irish. Both amazing wood carvers. Ive learned most of what i know from the web. A good place, and a forum im part of, is lumberjocks.com