Every style guide on this site assumes one thing is already handled: the boring, practical essentials that have nothing to do with aesthetic and everything to do with getting through a semester without a daily inconvenience. Here's the actual checklist.
Bathroom basics come first
A portable shower caddy with a carry handle and real drainage is the single most-used item on this whole list if you're in a communal bathroom dorm — buy it before you buy anything decorative.
Command hooks solve more problems than you'd expect
Most dorms don't allow nails or damage-causing adhesive, which makes a value pack of no-damage hooks one of the highest-utility purchases on a move-in list — for towels, bags, string lights, and anything else that needs to hang.
The items nobody posts pictures of — hooks, caddies, sheets — are usually the ones you'll actually reach for every single day.
Get the sheet size right the first time
Standard Twin sheets do not fit a Twin XL dorm mattress, and it's a surprisingly common first-week mistake. Double-check the sizing before move-in day, not after.
Towels that actually fit your closet
A quick-dry bath towel set sized for a dorm closet, not a linen closet at home, dries fast enough that mildew never becomes the problem it can be in a shared bathroom.
Shower shoes are not optional
Quick-dry, slip-resistant shower shoes are one of the least glamorous items on this whole site and one of the most necessary for any communal bathroom situation.
None of these are exciting purchases. All of them are the difference between a dorm room that functions smoothly and one with a small daily friction point you didn't need.