Store credit cards typically have higher interest rate than a regular credit card. It's very tempting to purchase a lot of things when you are given a card with a 5000 dollars credit. At the time, you don't think you will have to those 5000 dollars plus the interest rates. It's almost impossible to not spend with those cards. So my recommendation would be to just never accept one.
Be ready for an emergency
Emergencies like a car accident or an illness are two of the leading causes of debt. We all want to live a happy life and we do not like to think about the bad things that can happen to us. Unfortunately, if something bad happens to you and you don't have enough money to pay for the medical bills or the car reparation the situation is going to be worse.
However, to avoid debt you do not need to think about the worse that can happen yo your every day. Just make sure to have some a good insurance and also money in the bank to face emergencies.
Purchase a product only if you have enough money in your bank account
For example, if you want the new plasma TV but you can not afford it at the moment wait until you earn enough money to buy it without a credit. The really cool thing about that technique is that it can really motivate you to work harder. Getting a credit to buy the things you want the most is the easy way. If you just buy when you can afford it is a lot more rewarding.
As a matter of fact, it's one of the principles of a wealthy mindset. Wealthy people always know they can work hard enough to get what they want without risking debt. So the best advice I can give it to you is to trust your ability to make money.