Toilet Paper

Toilet paper is very underappreciated. The only time you ever truly realize how important toilet paper is, is when you run out. That is the moment where you'll have to rely on either a roommate or family member to rescue you. If you're living alone, you might be in a bit of trouble. To avoid this problem, you just need to get into the habit of keeping a stockpile of rolls within your bathroom. The only time you need to restock is every few weeks/months, when there's only two or three rolls left.

I should also mention, that you should always check if a public bathroom stall is out of toilet paper (just to get into the habit). This should hopefully be self explanatory.

You know what they say, better safe than sorry.