There are some things you know you shouldn’t do. Driving over the speed limit, washing dark laundry with white linens, and frying bacon in the nude are just some examples of the things in life you know are a bad idea. Whether you do them is an entirely different matter, and if you do, you commit to them knowing full well the consequences.

When it comes to your budget, on the other hand, it’s not always easy sussing out the shoulds and should nots. As a result, you can end up making major financial mistakes without even realizing it. And the consequences? You could limit your savings potential for years.

Have you started panicking, wondering if you’re committing any heinous budget mistakes? Don’t! We’ve got you covered. Take a look at these life hacks for saving money, so you know what you shouldn’t do when you make a budget.

Wing It

On a cool winter Saturday, the last thing you want to do is pour over your finances and fiddle with the calculator. There are kids to look after or sleep to catch up on if you don’t have them. You have a list of chores a mile long, and then there’s the fact you’ve been meaning to binge watch David Fincher’s Mindhunter for a while now.

When you take all that into account, it can be hard to force yourself to budget. You may feel tempted to take a guess at your income and expenses to help expedite the process. In a word: don’t. Winging your budget is just as bad as having no budget at all.

Your financial plan needs accurate, concrete numbers if you expect it to help you save money. Go through your financial statements and categorize the last six months of your spending. Don’t just figure out how much you spend on the fixed expenses (like rent and utilities). You’ll want to know how much you spend on variable expenses (like groceries and entertainment) in a typical month. Once you have a good idea of how you’re spending, you’ll find it easier to pinpoint bad habits in overspending.

Mistake Gross for Net Income

At the end of the day, you make what you make, regardless if you call it gross or net, right? Wrong! This is a common mistake made by novice budgeteers that can end up throwing your whole budget out of whack. These two terms represent two very different figures.

Your gross income is the total amount of money you make from any employer, benefit, or side hustle you have before any deductions are taken off. Once you subtract taxes, insurance payments, and—in the case of a side gig—any expenses from your sales, you’ll arrive at the net income. It may be significantly lower than your gross, yet the net is what’s deposited in your bank account.

If you use gross, your budget won’t tally properly. You’ll assume you have more money to spend than you do, which can lead you into trouble very quickly.

Ignore the Unexpected

In using your past financial statements as guidance, you’re missing one key detail of your budget: unexpected expenses in your future. Nothing in the last six months can predict when your furnace will stop working, your fridge will start leaking, or your cat will swallow a hairband in the future.

As you table your financial plan, you need to try to predict these occasions before they ever happen. You don’t necessarily need to be psychic enough to identify the emergency by name, date, and price, but you do need to put away cash to cover these expenses whenever they happen.

Be cautious when you create your budget, and make sure you have enough savings going towards an emergency fund. This self-made safety net can save you from taking out instant payday loans or relying on your credit card. While both are practical ways to cover things you can’t afford, they can’t compete with the sense of satisfaction you’ll feel for covering debts on your own.

Personal finances don’t come easy to most of us. Unlike the rules of the road or the grease spitting distance of bacon, many of the tricks and tips regarding your budget are learnt through trial and error. At least now you’ve got a few pointers down pat, so you can start discovering the best rules to govern your finances by.