Do you ever look back and wonder, “What if I had known this when I was 18?” I know I do. It’s not that I live in the past and berate myself for mistakes that I’ve made. The school of hard knocks is a great teacher, and I know there are lessons I learned the hard way that I will always remember.

But if I had to live my life over again, there are a few lessons I would like to have learned a little earlier in life.

1. Just because you can pay the minimum doesn’t mean you can afford the balance. It took me years to figure that out. For a long time I was a creditor’s dream come true. I carried a large balance on my credit cards, and faithfully paid the minimum balance by the due date every month. I thought I was doing great, because my credit score was great. I never thought to add up all the interest I was paying on my purchases.

2. If you begin investing for your retirement early, you won’t have to invest as much. My husband and I began investing in our retirement when I was 34. Yes, two years ago. Had we known about compounding interest, we certainly would have invested sooner. I’m not really that worried about what will happen to us when we’re older, but things surely would have been easier if we had gotten our financial lives together sooner.

3. Don’t spend a ton of money on your education until you know for sure what you want to do. My major in college? Sociology. Do you know what I’ve done with that degree? Nothing. How much in student loan debt did that degree cost me? $4000. But wait. It gets worse. I went to graduate school. For what? Special Education. Did I finish the program? Nope. How much did that mistake cost me in student loan debt? $10,000. In retrospect, I should have thought much harder about my education before taking the plunge.

4. If you’re going to pay a ton of money for a college education, you should at least show up for class. I don’t even want to think about all the hours of class I paid for, but didn’t benefit from. I went to all of the classes that interested me, but if I found a class boring, I would skip the lecture and skate by on my test taking skills. I didn’t get nearly everything out of college that I could have.

5. Spend less than you earn. I went over this yesterday. It’s a concept that I’ve only recently taken seriously. When I think about all the money I’ve blown on going to the movies, eating out, and just basic useless stuff, it’s kind of depressing.

Obviously I can’t turn back the clock and live my life over. That’s OK. I’m confident that my husband and I will be alright, despite our mistakes. Life won’t be as easy as it could have been, but we’ll be OK. The one thing I can do is make sure my children learn these lessons before they leave home. Then hopefully they won’t make the same mistakes I did.

What lessons do you wish you had learned earlier in life?