who can tell me how to save money?

I am perplexed about how to use money well since I was a university student. That is, I do not know how to manage money. Although I keep accounting but I feel my money flow away like water. Every time I open up and check my purse, I remind myself not to put extra money in it. However, I still put some to make myself feel better. Due to this reason, the number of my bank account decrease day by day instead of increasing.