Ok so what I like to do to keep things straight is at the top of my main script page have major events, things that are not allowed to happen, and any important details. A general summary of the story at the top helps me as well.
If you don't know who is drawing yet then I think it's important to keep in mind how much imput will the artist get. On my script I like to let the artist have wiggle room for their ideas, so I only put in the items that are really important. Specific actions, dialogue, and things that really need to be in the scene.
I hope this helps.