Best offer on the table right away or hold some $ back for negotiation?

Depends where your offer is going to line up relative to the market, and how you think it will be taken. You don't want to be insulting or unrealistic; and if you really want the potential hire AND they're a negotiator, then they can push you higher than your "best offer" anyway.

How much do you want them?

you'll probably have to provide some more context to get a good answer