All good advice so far. . . I'll add:
Don't push yourself past your experience level -- healthy fear/respect for how much a tree can kill you is a good thing. Trees usually don't hurt you just a little, or just kill you part ways.
Stay on flat ground for now, sloped ground adds many new elements to the game.
I was falling some Larch the other evening, and I had a close call. I was on steep ground, and the trees had a head lean up hill. It's hard to move fast on snow/ice on the steeps -- it makes it harder to get clear.
There was a belly in the hill, and I knew the butt was going to kick out. I had a hard time moving back on the slope (I should have had my caulks on), and I wasn't far enough back. The tree went over, the butt kicked back, took a second bounce -- and hit me square in the shins.
I went for a little ride down the hill, and so did the saw. Luckily it wasn't a larger tree. . . The only thing that was bruised was my shins and ego -- and some blood for good measure.
Point is, even when you see stuff coming, you can't see stuff coming. capisce?
Make a clear escape route, don't saw under the lean if you can help it, Look up look out!, wear some safety gear, and get some good tutelage if possible.
Good luck!