I've always told people that if you are over 150 pounds, don't climb. All the equipment advice has been given above and that is extremely important to follow. A man lift rental or buying is your safest option and there are 4x4 self leveling options out there that can get into most spots. Hunting equipment for tree stands and recreational climbing (or anything of the sort) is and absolute no no! There are reasons the equipment is different as you can cut through your rope, leg and so on if something goes wrong. You need the proper stuff, period. But what hasn't been mentioned is know the tree you are cutting! Not all trees cut the same, some break fast, some split and clap and that is no fun getting a foot, arm or your body sucked in. Others can be rotted half way through and be unpredictable. Never leave a dead man hanging up there, if you can't or won't bring/drop to the ground what you cut, don't even start. Understand the trees around you so you can avoid hangups in other trees, these when freed up can come at you like a missile and when you get hit, it will damage your body. Get training, practice climbing with 100 pounds hanging from you and never, never do this without a spotter. Make sure this person can call 911 when needed and not panic. This is all assuming you are cutting real trees that are lets say over 40' up to 140'. Even smaller can kill you though.
As back ground, I was taught by my logger FIL. Spent 10 years training with him on about every type of tree in the PNW. I climbed for close to 30 years and it is physically demanding hauling up you fuel, saw and gear while limbing as you go. After an incident on the peninsula where my spotter freaked out, I no longer climb. There may come a time where you need to trust your gear with your life and need to jump/push off to try and avoid getting nailed or sucked in... if you are unwilling to do that, don't climb. There is a reason most tree services use lifts these days. Not everyone is geared for his type of work, I tried to teach one SIL how to do this, after he froze at 30' it was a royal pain in the A to get him down in one piece even though I was tempted to just drop the tree with him in it, in hindsight... I should have