I keep seeing the words "credit score" in this forum when what I think you mean is your FICO score (VERY different). Each credit reporting agency "scores" differently. FICO uses all three credit reporting agencies' data and scores range from 300 to 850. I strongly recommend you read this:
Also, someone in this forum said that paying cash is the worst thing you can do! I have lived on a cash basis for 7 years now and find it INCREDIBLY liberating. Each time one of my collection accounts dropped off my credit report, my score went up. I haven't used credit at ALL and I'm now considering buying a house at the beginning of next year when everything negative is off my credit report and I've saved a little more money.
Over the last year, I have applied for and received a gas card, a furniture store card, and two department store cards. (My credit history is 33 years.) I will apply for a major credit card as soon as I find one that doesn't charge an arm and a leg just for HAVING it. I have no intention of charging anything on any of these cards unless I already have the money to pay it off (just a stupid exercise to decrease my debt-to-credit ratio and increase my available credit, which in turn, increases your FICO score!)
If you can possibly do it, I HIGHLY recommend going 'cardless'. I realize that many people are in dire straights right now and NEED the help their credit cards can give them, but if at all possible, DON'T get caught up in it! I kinda took a Mary Poppins approach to spending and decided to make a game out of not spending. I LOOK for ways NOT to spend money. You'd be surprised how much you can do without and NOT change your lifestyle! Save your credit for a BIG purchase (like a house) and use cash whenever possible. Learn the difference between a NEED and a WANT (I do not NEED a new address book. I WANT a new address book.) What I need is DRAMATICALLY different than what I want!
Remember that your possessions do not define who you are. It's what's INSIDE that counts. You can't buy that with or without a credit card!