The best thing I did [almost 30 years ago] to save money was to write down EVERYTHING I spent for 2 months. That means everything IN DETAIL - every item from the vending machine, every beer after work, every magazine, everything. I even broke down "groceries" into food/necessities then each non-essential was listed separately.

Yes, it took some time but it was only for 2 months.

When done, I reviewing and summarized the list. I was amazed at the unnecessary things I was buying and how much they were really costing me. Even before I summarized things it was becoming obvious where some of the issues were. That changed my spending habits permanently. (OK, they got a little lax over the years but I'm pretty sure I have more to spend now as a result of that one exercise.)