I recently bought a bookstand from like Staples (link:
https://www.staples.com/Staples-BookLift-Copyholder-88980/product_515621 for ~$12) that theoretically can handle textbooks, so the idea is instead of the textbook flat on a desk or table and bending one's neck for hours at a time day after day, it adjusts the tilt angle so the book comes to your eyes instead of vice versa.
It's cheap, plastic, and portable, and I'm sure there's better models out there, but it's one thing that only in hindsight I wish I had bought for myself, even in undergrad. Better late than never. [Edit: I cannot yet vouch for the quality of this bookstand... it's flimsy to be honest, but it's better than nothing.]
Correct posture and ergonomics while sitting in class, driving, and sitting at a computer are gigantic subjects that can't really fit into one post. Like, laptops are lose-lose for posture, since if you have the laptop keyboard properly low enough to type on with correct ergonomics for your wrists/arms/shoulders/etc, then the screen is much too low for your eyes/neck. But if you use a laptop stand (which everyone here should buy for home use!) the screen is elevated enough so it's eye level, but the keyboard is then far away from you. Best is to plug a laptop into a separate monitor and separate keyboard/mouse when using it at home. And use a laptop stand too.
So at the very least for computer use at home, any poor student should probably invest in at least a laptop stand ($30-50ish), external monitor (even an old one lying around), and separate keyboard/mouse (even cheap ones), something like this:
All of those investments are cheaper than even one MRI (usually) +/- months of physical therapy. Promise! At least that's how I can sell the idea to young whippersnappers here to give a darn.
Next step up -- and I think WTFrequency sold me on the idea -- is to get a thingy (what's it called?) that's the poor person's sit-stand desk:
There's cheapass sit-stand desks for $200-300, but I kinda wanna invest in a nice American made one that's like 6 feet wide at least, and the ones I want are close to $1000+ so currently not in the cards.
Edited to Add: I recently bought some PT books by Robin McKenzie (e.g.
Treat Your Own Back, Treat Your Own Neck, etc.), allegedly some famous DPT dude from New Zealand who's known for his technique ("McKenzie Method") of physical therapy. I'm skimming the books (and this is obviously not medical advice!) but apparently a lot of the thoracic and cervical spine support depends on having good lumbar support first (when sitting), so either an office chair that has really fancy lumbar support (and these can get expensive) or buy a lumbar cushion for use at home or even when driving:
Note: These are random images from the Internetz and aren't necessarily the "best."
I feel like these are all things you see old people in their 60s buy, but why the heck not learn and practice good posture in one's 20s and 30s before degeneration and arthritis and other issues screw us all over.