Track everything for several months. I use a simple spreadsheet template, you could use a book or an notes app, whatever works for you. The key is that every time money is spent, you make a note of it.
Then you can start to fit spending into categories, and can start to anticipate what your future spending will be.
Things will always come up unexpectedly, or because you forgot about them. I pay for some things annually, so tracking for a few months won't reveal those annual costs.
Use two bank accounts. One is your main bills account... wages go in there and your direct debits come out. One is your everyday spending account, where you transfer over your food budget, your clothing budget. You could do that monthly, or weekly. You spend from the from everyday spending account, and when the money is gone... it's gone. You could divide that account up into pots, naming them food, clothing etc. Monzo has pots, Starling has spaces. Your bank will call them different things but they are just a place holder for money which can be quickly moved to spending part of the account.
You may find it helpful to read books, listen to podcasts, about personal finance.
Meaningful Money episode on budgeting: meaningfulmoney.tv/2023/05/24/finance-os-budgeting/
What are you saving for? Give it a purpose. Initially that may be an emergency fund, a pot of money which you can use on unexpected events rather than taking out debt. Be intentional with your money. When you spend money, think about why you are buying, what is it for.