This is the true answer, especially for such a broad question.

You dont need to be fancy about it either. When I started I downloaded a years worth of credit card transactions and put them in a spreadsheet. I took the time to go line by line and assign a category for it.

Then I made a chart and could visually see where my money was going. On top of that I then calculated each category as percentage of my annual salary.

It’s very eye opening. Even things that aren’t an issue at least I now know that so don’t need to feel worried/guilty about it.