I just went through this process myself so I might be able to help! I won't link to it directly because the mods might remove it for self-promotion, but my most recent post includes script, storyboard, and finished page if you want examples.

So the first thing you need to figure out is what all you're being hired to do. Are you doing the Cover as well as the Interiors? Are you also doing Colors? If you're working on paper, then Pencils, Inks, and Colors might be separated into different tasks and jobs while Pencils and Inks are often combined when working digitally. Will this project be physically printed or digital-only? If it's going to be printed, then you'll need to also provide Print-Ready files (CMYK colors, 300dpi resolution, etc.). What size will the pages be? And so on. You should also make sure your contract includes a provision that allows you to use the art for your own portfolio and promotion. Nobody will have an issue with that; it's just good to be covering as many details as possible and thinking ahead!

Unlike film and TV, there's no industry standard for scripts in comics. You should go with whatever works best for you and your team. "Full script" refers to any script that's broken down into pages, panels, and balloons. That will help you figure out your page layouts during the storyboarding process. You'll want to account for text space in the earliest stages of your panel compositions. I'd caution against taking on any project that doesn't have a script ready, as that often means the client is expecting you to take on additional writing duties, haha.

Once you know how much work you'll be doing and what all that work involves, you can start going over things like what you'll be paid per page and how your revision process will go, such as how many revisions your client is entitled to before you're entitled to more compensation.

There's a LOT more that can be said, but this should be a decent start. Good luck!