[tobinharris]

Whatever you decide will probably be wrong.

So I'd try and set your sales guy up for success, get him off to a positive start, and be generous with commission. Agree targets that should be achievable.

If he's amazing, you'll want to agree something attractive to both of you. Possibly involving equity. If he can't sell your stuff, then you'll probably want to try someone else. So you'll need the ability to "undo.