Let me drop a few suggestions from a 2L on what I found useful and what was a waste of money.

Useful:

1. a book stand. While not necessarily the best for highlighting and taking notes in the book, it is great for read week and reviewing the material to put in your outlines. Obv. contingent on using the real book as opposed to a digital version.
2. TABS, the legal industry keeps the tab industry alive. Do yourself a favor and tab your books according to the chapter/topic you read for each class. This will make reviewing and open note exams 100% easier.
3. you're gonna learn how to brief a case, you'll type up case briefs and blah...blah...blah. By 2nd semester, or by 2L you'll likely stop briefing cases. It's too time consuming and you'll have learned how to read a case by then. INSTEAD invest in the 36 pack of multicolored highlighters. Think up some color coordinated system for the different parts of the case (Facts, issue, plaintiff argument, defendant argument, holding, rule) and color code them. Then when you get cold called boom your look for the color that is associated with the info you need. Life saver.
4. A fricken calendar/planner. You WILL have a million deadlines. It's gonna happen, you're not special, you cannot remember them all. Get a planner and USE it. Using your digital one on you computer is fine as long as you remember to actually add your stuff to it.
5. The Pilot Precise V5 retractable is the superior pen. I will take no questions on this matter.
6. A water bottle. Stay hydrated friends.
7. A lunchbox. Don't be like me and spend too much money on unhealthy foods. Pack your lunch. I believe in you, bet better than me. See also coffee travel mug for reasons why this is a good idea.
8. A coffee travel mug. If you tally up the amount you spend on starbucks in the 3 years of law school ((2 coffees/per day x $5/coffee) x 30 weeks/year)x3 year. it's like $4,500. Here is a luxury suite 7 night cruise to the Caribbean you could afford with just a few extra dollars added to that money.
9. A locker! when the school offers them, get one. See book bag below for details.
10. mental health habit. for me its a meditation app. For others it's a gym membership. You need something to keep you sane. If you have to spend a few dollars on a healthy habit to keep you from jumping off the roof it's worth it. (seriously guys, they lock the balconies during finals it's rough sometimes. Take care of yourself).

Waste:

1. a printer. yes, sometimes it is handy. The expensive ink isn't worth it. You're pay big $$$ print on the school's dime.
2. A fancy bookbag. Look, I get it. You wanna look professional, you want to look stylish etc... I bought a really nice leather messenger bag. I love that thing. It's entirely unusable for law school purposes. You'll be carrying around approx. 1 ton of legal textbooks. Get a big, sturdy bag. I'm rocking a High Sierra heavy duty bag if i'm lucky it will survive til graduation but after 2 years it's look ROUGH.
3. a pinboard. nice to have at your home desk. mostly useless.

Honorable mention:

Quimbee: great resource cost a few hundred bucks. Will likely save your ass once or twice. USE WITH CAUTION. it can and will become a crutch if you let it. In the beginning read the cases, struggle to understand them, learn HOW to read a case. Use quimbee to check your work. Once you know how to dot he thing Quimbee is fine to use when you're short on time or whatever, but if you don't build those critical reading skills from the beginning you are only hurting yourself in the long run. Also, they have great practice questions and commercial outlines for some subjects.