I'm a college student, so "budgeting" for me is more like "debt minimization", since overall I'm spending >10x what I make working on my education/living expenses.
As far as day-to-day living:
Sharing all my textbooks, I live with 2 other people who are in all the same classes as me, we each bought 1 textbook this semester. Since I purchased an international edition I spent $20 on textbooks instead of the standard $400
Food: I live on rice/beans, pasta with homemade sauce (not only cheaper, but a LOT tastier), peanutbutter sandwitches, etc.
Drink: I drink a lot of tea and coffee now, and I got an espresso maker so I can have my caffeine fix without being tempted by the starbucks on campus. As a side note, I've also finally realized just how bad starbucks espresso really is.
Clothes: I do tend to spend a lot on clothes, because I'm an awkward size that's hard to find used clothes for (30x34 pants and medium-long t-shirts), and I tend to kill clothes fairly quickly because I'm a clutz. But I'm trying to work on a solution to that
Hygene: I switched to using a double edged razor. The Merkur 23C cost me around $30 bucks, and blades are dirt cheap. The handle paid for itself within a single pack of blades vs. a gillete mach 3.
As far as hobbies:
My personal rule isn't so much on budgeting my hobby purchases, but on never buying something unless I can break even when I sell it. That's why my audio purchases tend to be DIY or vintage. The only real net "loss" from my hobbies is music purchases, but I can live with that. The music is lifesaving.