Free: Contests & Raffles.
The most expensive decision I ever made, (except for deciding to marry my now ex-wife ) was when I started wildlife photography. So be forewarned, the quest for true high quality wildlife photos is expensive and highly addictive. If quality is your goal, then glass will be your first priority. A great lens with a mediocre camera will produce better results than a great camera with a mediocre lens. So the short answer is buy the best telephoto you can afford. Don't get me wrong, lots of pros use teleconverters, but they are using them with high quality lenses so the inherent loss of quality becomes negligible. TC's multiply more than just the image size, they multiply every defect in your lens' performance as well, including a drop in light transmission. Which makes getting decent pics in low light situations, (when most wildlife is active) more problematic. There are lots of options but no free lunch, I'm afraid.As far as honing skills, there are lots of books, websites, and U-tube tutorials available, and then practice, practice, practice. Good luck and welcome to "Catch and release" hunting.
Steve Perry Backcountry Gallery has a lot of tricks and tips
Honestly, get the best glass you cant afford. Im not sure good glass has ever really come down in price, even used many hold their value unless they have beaten around in the back of a truck. Teleconverters have a place, but utilized best if shooting a prime lens. I occasionally get some nice shots with a teleconverter but certainly not THE SHOT. Many times they become "document" type photos, not the one you want blown up and on your wall. That being said, telecoverters are like $200 or two tanks of gas, so you probably should have one in your camera bag.
to add onto bd's post, obviously there are better lens companies than others. who is the best bet? Im in the same boat and luckily have a family member into photography but is 2000 miles away. shes sending me a 2x extender to use. I have a 75-300mm canon lens with a T6 body (entry camera i know). should you stick to body specific lenses or look at someone like sigma lenses?