Ugly sketches - don't make them too pretty. They should be quick and "ugly" and tell you just enough about the idea to make an informed decision and compare it to other ideas.
They can be in black-and-white or in color. Trying out color ideas at an early stage is a good idea.
It's a good thing to not feel "locked in" by a too detailed sketch. The production phase should feel joyful and dynamic, not that you're just going through the motions and doing what the sketch tells you to.
Prioritize SHAPE and COMPOSITION. These things are the most important and will ultimately make or break your work.
(Excellent resources on this: books by Jack Hamm)
They can be in black-and-white or in color. Trying out color ideas at an early stage is a good idea.
It's a good thing to not feel "locked in" by a too detailed sketch. The production phase should feel joyful and dynamic, not that you're just going through the motions and doing what the sketch tells you to.
Prioritize SHAPE and COMPOSITION. These things are the most important and will ultimately make or break your work.
(Excellent resources on this: books by Jack Hamm)