RE: What to do to improve precision with crossbow?
Welcome to the forum! What country are you in? What kind of shooting experience do you have?
My best advice for you is to practice as much as you can. Practice shooting off-hand as much as possible. Pretend that every shot you take is the only shot you take. When you are shooting remember trigger control, sight picture, breathing and follow through. Limit the number of shots you take so that every shot is taken carefully, if you tell yourself that you will only shoot ten shots then you will be more careful.
I've been shooting too long to tell you what my groups were when I started. What you should expect is different from from what I expected because our experience is different.