If your name is out there, people will come to you.... "networking" helps too.... knowing guys that do dirt work, home building, farmers, etc. The thing is you kind of have to be "big" before you can really be known.
I always keep my eyes open for trees. Last year we pulled a good 300+ cords of logs off properties that they would have either dozed off into the fence line, burned, chipped up, or shoved off in a pile with "free" and had every crazy with a truck and Wild Thang in there.
Often for free or just some minor horse trading.
Have deals worked out with a few larger land clearing guys to get the logs and in return we give them some firewood or lumber.
It also doesn't hurt to figure out what the foreman likes to drink/smoke, etc and bring it by when you go asking "Hey.... what's going on with all those logs".
Then there are timber sales. Here they are sold by the state or borough (that's a county for the rest of you guys). Usually the tracts are 50-100 acres, sometimes smaller or larger though. They have a 300ish acre tract open for bid now, min bid is around $70k.
If you win the bid you get a timeline (often 1-2 years) to get it all cut. Pretty much you are buying the permission to cut the wood and that's it. The thing with those is before they award it, you have to have a written plan on how you plan to do the work, what types of equipment, etc.
I doubt they would allow a guy with minimal equipment to go in on a big tract... they want to see a "normal" logging outfit... feller bunchers, skidders, dozer, log trucks, etc.
Up where I'm from in Maine, alot of the big mills contract out for woodcutters. I was visiting about a month ago and the radio had ads that JR Irving (big outfit) was looking for contractors.
Those are nice jobs because the mill does alot of the leg work. Pretty much you just haul in x amount of wood a week under the contract for x price and they tell you were to cut. They have their own forester and all that. You just provide the equipment.
I'd imagine this is pretty common in other places too... seems like on the Swamp Logger and Axeman show that is how they are doing it as well.
There is a Huber mill in Crystal Hill, VA that makes OSB, I bet they have openings on contracts at times. I'd imagine there are other mills too, just I know that one.
http://www.huberwood.com
Good people at Huber, my Dad is going to retire soon, been working for 32 years for Huber.