Compensation negotiation for preliminary editing

Hi, wasn't sure if this should go in Journalism or not but here we are.

Anyways, I've getting involved in an athlete's book project. It's basically a memoir but I don't want to go too deep into that because that's not that relevant here. He's not a big name but the book isn't built on star power, rather the stories contained in it.

I haven't been involved in any freelance work quite like this before and I was just looking for tips in terms of negotiating with the author. I'm keen to the rule of not really looking at it, or offering much of anything without being compensated. But the plan is to start off with some preliminary guidance for him and be sort of the first eye that sees his work other than him...basically just an adviser for now. What's fair ballpark range for compensation here? And any other relevant advice would be great. Thanks.

 

$25-$35 per hour.