As a professional
chainsaw operator and logger I can offer some tips I believe...
First, buy a
Stihl, it need not be a big fancy one but I wouldn't use anything else.
You'll need some mixed gas and bar & chain oil. 2.5gal of gas should go more than all day in a little saw, your bar & chain oil consumption should be half of that or less.
You'll need some tools to keep it sharp:
A round file for the cutting teeth, with a guide preferably to do a better job with less room for error.
A filing gaugle to clean the sawdust out of the bar's channel and measure your rakers height, etc.
And a flat file for filing the rakers down to the proper level.
Parts to have on hand:
Ideally replacement parts should go: 3 chains, 2 sprockets, 1 bar...
A spare bar is handy to have just in case, a spot-welded bar is sufficient for regular/non-professional use and cheaper to purchase.
Do not be without a spare
chain!
Sprocket: Get at least one, they're cheap!
Cutting Techniques:
I'm not a feller so I can't speak on that much other than watch the lean and retreat at a 45 degree angle after your finishing cut.
Watch the tip of the bar!
If you're cutting two trees that are parallel don't let your tip touch the one you aren't cutting. I won't say don't cut with the tip, just don't do it accidentally!
When limbing watch that tip! It's real easy to run the saw down the the upper side of the tree parallel with it and right into your leg. Don't do this!
Watch your cut so as not to pinch the saw, it's very annoying and can destroy the bar in some cases. Out in the woods we very often need a machine to life the tree the to get the saw out. If you have a spare bar and chain you can take off the pinched one and go to work with the other. Sometimes you can remove the powerhead and the bar will come out and the chain will come after. Don't count on it though.
Kickback: It will happen eventually if you're cutting enough. Be prepared for it, maintain a firm grip with both hands. Keep your left elbow locked if possible. Not letting go with your right hand will go a long ways too! I've had a few scares, but like someone said above, I haven't hurt myself with a running saw. Have scars from chain sharpening/inspecting, etc.
Sorry if this isn't organized the best but I've been collecting my thoughts for a while and hope I didn't forget toooo much here. If anyone has any questions feel free to contact me and hopefully I'll know!