Alex de Campi has posted some very frank numbers about page rates that should give you a good range to work with:

There’s also a website called Fair Page Rates with similar info:

As far as the contract/control goes, that’s harder for me to advise on. It depends on whether it’s creator-owned or work-for-hire and what their expectations are. I personally have no problem doing work for hire on someone else’s property and not owning that work as long as I’m credited properly and paid fairly. On creator-owned work I’m much more picky about control and ownership.

That said, everyone’s expectations are different and early on in your creative career it’s a lot harder to get every contract stipulation because you also want the experience/credit and are a bit desperate (and many publishers know it).

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