If you take one thing off this page, take this: hire a consulting forester before you talk price with anybody. A consulting forester is hired by the landowner and works for the landowner. That is the whole difference. A timber buyer or a procurement forester is competent and often perfectly straight, but they are paid to buy wood well for the mill or dealer that employs them. Their job is not to get you the top dollar.
What the consulting forester does first is find out what you own. They walk the tract, mark the trees to be cut, and cruise the timber - sampling plots across the stand to estimate volume by species and by product. That cruise is the single document that changes the balance of a timber sale. Without it you are negotiating against somebody who has walked the property with a prism and a tally sheet while you are working off a guess - the arithmetic behind a prism plot is on this site if you want to see what he is doing out there. With it, every buyer is bidding on the same defined lot, and you can tell a good offer from a poor one.
Consulting foresters are usually paid a commission on the sale price or a negotiated fee, and they will tell you which before they start. Ask what the arrangement is, ask for references from landowners they have sold for, and ask whether they will administer the harvest as well as sell it - somebody should be checking on the crew while the job runs.
Your state forestry agency and the land-grant extension service also run landowner assistance programs. They will not sell your timber for you, but they will walk your ground, talk through management options, and point you to registered or licensed consultants working in your county. That help is a phone call away and typically costs nothing.