As a student, money is almost always a problem, so much to buy with so little, if you know you're not a 'baller', 'lagos big boy', 'alhaji', 'slay queen' or anything of sort, the first tip is stay indoors as much as possible lol, the best way to save money is not to spend money, don't put yourself in a situation where you'd have to spend what you don't have, however if you must go out at a time when you do not have the disposable cash, look for house parties, they are usually free with free drinks, small chops, food etc. 

Lets keep this simple. Ever heard of the 50/30/20 thumb rule? No? It basically means 50% of your total income should be for necessities like housing and bills, 30% should be for wants such as entertainment and 20% should be saved.