Budget

A business would never operate without a budget and neither should a family.
At the beginning of each new month I sit down and estimate income and outflow.
There are lots of budgets to be found online or make up your own like I did.
Some items are fixed amounts like the mortgage payment, car payment, insurance payments, etc.. Some items are not fixed like groceries, meals out, even some utility bills.
If you have never budgeted before you may want to start out by tracking your spending for a month and see where your money goes. From that point you can figure out what amounts are prudent for a particular category.
Only when you know where your money goes can you make good decisions are budgeting your money. The important thing is to start today and be consistent.