Besides the info about the protective equipment, I would suggest you take a close look at the first cut or two you make. Grab up a handful of chips and put them in a bag. After you have cut for 30 minutes, compare the chips. Then again a little later. What I'm getting to is that as the chain dulls the size of the chip will get smaller. Don't wait until your saw is throwing sawdust to stop and sharpen the chain. Many newbs burn up good saws by forcing to to cut with a dull chain. It might be a good idea to buy a spare chain to reduce the temptation to keep going so you can get finished. Stop and sharpen or change. There are a couple of things in your situation that will dull a chain fast: buried metal and plunging the bar tip into the dirt. The first one is often beyond your control; the second one is totally up to you. As you near the finish of a cut, slow down so that you can control the tip and not let it nod into the dirt.
Another tip-
If the butt of the log and the top of the tree are both laying firmly on the ground, it is likely that the upper part of the middle of the log is under compression. If you cut from the top of the log toward the dirt it is likely that as you remove wood from the kerf, the log will close and pinch your bar. I prefer to cut from the bottom of the log upwards in those situations. You can also use a wedge to hold the kerf open and avoid pinching.
