Much of what goes wrong in the world or in business can be blamed on bad decisions. Yes, natural disasters and other events happen that no one can control. But even when those happen, just how well we cope with the aftermath may depend on how carefully we thought things through in advance.

Too often, we go on automatic pilot and just plain don’t think about the consequences of our actions. If you’re the parent of a teenager — in fact, if you just follow the news — you already know this. But let’s be honest with ourselves: all of us can make this mistake, and not just teens or politicians.

There are some foolish mistakes in business that people make time after time, even though it seems they should know better. Here are a few of them. Let’s call them ten ways to hurt your business.

10. Buy something just because “it’s deductible.”

Ahh, deductibility. That may be the most insidious seducer of fledgling business owners — and many experienced business people fall for it, too.

While it’s true that every legitimate business expense reduces the income on which you pay taxes, we often forget the other half of the story: Every dollar you incur in expenses first has to be earned as revenue. Remember, too: For each dollar you spent on that thing you didn’t need, the tax deduction got you only 20 or 30 cents back.

9. Don’t take credit cards.

So you think letting customers pay with plastic is too risky, or requires too much work, or costs too much because the credit card company takes a cut from every sale? Fine. Just don’t think about how much more it costs when your competitor gets more business from the growing number of customers who use credit or debit cards to pay bills — especially the ones in three figures or more.

8. Rely too much on credit card debt.

Used carefully, credit card debt can help you smooth your cash flow. And with low- or no-interest teaser rates, you can cut the cost of that debt to virtually nothing. The danger is getting over your head. Don’t take on this kind of debt — if fact, don’t take on any kind of debt — without making sure you can pay it down in time to avoid huge interest expenses.

7. Cut your prices just to beat the competition.

Face it: If all you’re competing on is price, there’s always someone who can charge less money. Yes, you have to pay attention to market prices for your services, but if you’re going to stay in business, what you really need to do is make sure you deliver value that brings good customers back.

6. Save money by not advertising.

No question, the media marketplace is changing as the Internet becomes a more important source of information. But old media — radio, TV, even newspapers — aren’t dead yet. You know the old Bible verse about not hiding your light under a bushel. Not advertising is one way to snuff that candle right out.

5. Under-insure (or over-insure) your business.

Not getting enough coverage can leave you vulnerable to a major catastrophe. But there’s a flip side: spending money on more coverage than you need. That maybe less damaging, of course, but who needs to leak revenue?

4. Save money by not hiring a bookkeeper.

What’s your No.1 job? Keeping the business going by finding customers and delivering service. You can’t do it all, no matter how small your operation. Keeping track of where the money comes from and where it goes is a critical job in any business. So find someone to track that for you. (And while you’re at it, go out and retain a good accountant to help you map out the big picture financially.)

3. Hire whoever comes in the door.

Yes, it can be tough to find good, skilled labor, but remember: You’re in the service business. Savvy employers know that hiring the wrong person costs way too much — in training, in turnover, in low customer satisfaction. That’s why they invest time in hiring people who fit their company.

Again there’s a flip side: relying on overtime instead of adding the staff you need. Overtime is best used to get through busy times of short duration. In time, if you work your people too hard, they’ll burn out.

2. Don’t get bids.

You don’t need to be a stickler about making sure everything you buy is competitively priced. An hour spent shopping prices for paper or printer ink may cost you more than just buying those items in the most convenient place. But relying on the same old sources time and time again, for everything, is a good prescription for spending more than you need to.

1. Don’t have a plan.

The old saying goes: “If you don’t know where you’re going, any road will get you there.” It’s true. And if you count too much on winging it, you’re pretty likely to fly right into the ground. But once again, don’t overcompensate. A plan doesn’t have to be etched in stone.

The best plans are flexible enough to change as circumstances warrant. And the simpler they are, the better. Because if you spend all your time planning, when are you going to do any business?