Every time you spend money write it down. Easier to keep track of your expenses if you see them on paper.
Once you know that amount and what you're using it on, you can make informed decisions as to where you can reduce your spending in order to save that money instead.
yes, a budget that you put down on paper/spreadsheet will probably show you some expenses you never really thought of, and its a good idea to add EVERYTHING, even small monthly expenses like $8/month for netflix should be on there, if you dont account for that stuff you're only hurting yourself