Must-haves for making a sweater the first time?

Super basic post! I’m waiting for my yarn to arrive and am trying to make sure I have everything else I need for making a sweater. I already have the needles and cables. I have a knitting counter as well. I blocked already with the same yarn but different color. Are there any “must-haves” you recommend for beginner knitters to use during sweater making? (for example, I’m seeing a certain kind of stitch marker- the locking ones- that people have used for the sleeves I think? but I’m not sure if those are necessary or a preference!)

Thanks!