I was lucky, I grew up around chainsaws, the the family members who taught us how to use them, knew what they were doing :cool2:
You have gotten some great advice, my best advice to you is to find a chainsaw dealer, not just a storefront that sells saws, but one that has a workshop fixes saws too.
Often, you can get a good deal on a slightly used saw, a lot of "Pros" who make their living with a chainsaw, will trade it in after a certain amount of time, depends on the guy.
If you can find a deal on a traded in, refurbished saw like that, you could be a lot of dollars ahead, and, if you buy it from a shop like that, you have somewhere to take it, to servicing.
Don't discount electric saws, I have two, a 12" Makita, that is fairly light weight, but with a sharp chain, it will cut big stuff...............
Little Makita
I also have an older Shindaiwa, that has a 20" or so long bar on it......
Shindaiwa Workhorse
..... it has amazing torque, and cuts well.
The electrics have the advantage of being quiet, and while they cut well, they do NOT cut like a good gas saw, you also have to drag the cord around, which can be a real pain if you are doing some limbing, it gets tangled up.
Chaps, mitts, steel toed boots, full face shield (I like the mesh ones, they don't fog up) and hearing protection, if you are running the gas saw.
Learn to sharpen your chain, do it often, you will save time.
Good luck, stay safe.
Cheers!