Asklemmy

Create a household account book. Either use existing solutions like apps, go the excel / sheets route (I did) or use pen&paper with a calculator to help you out.

Learn how budgeting works in the first place. This step is REALLY important! I recreated my household account book two more times because I was an idiot who ignored learning the bare basics on money and accounting. There's a reason it's a profession with proper wordings and not some obsure hobby. Use youtube tutorials for that, as you will need several examples to understand budgeting in general.

Once you've got that down, measure your income and expenses over a year. Estimate your last year by category and type of expense, write reoccuring yearly and monthly expenses down. Create a saving expense to build up a budget buffer. You WILL need a buffer for all the variations you inevitably will encounter throughout a year. Once you understand how much you spent monthly to stay alive, calculate how much you can spent freely (pocket money). Ideally, put that pocket money on a separate account with a separate card as access to it and "pay yourself" that pocket money. Your main account should be the houshold expenses account with strict rules on spendings. It's also where all your income enters to finance it.

If you'Ve reached this point, you will need to let it run for a couple of months to work out a lot of kinks in it. Food budget, mobility budgets, health budgets, etc. all need to be tuned to fit your needs. Whatever's left goes to saving or pocket money. That's up to you. Set yourself a minimal safety savings point that will keep you alive for half or a full year without (relevant) income. That's enough buffer for most expenses you will encounter.

So after all of this you should have a good understanding how much you spend on what. That's when you dive deeper and look into each spending category, including food and rent (often the two major expenses). Cutting out or replacing certain type of foods or drinks with cheaper alternatives have huge impacts on your available money.

The rest should slowly become obvious if you've educated yourself enough to reach this point. It's all about learning and understanding, really.