Let me share a personal story:
Once upon a time I was 18 years old and didn't have any credit history. I hated not being able to buy stuff or always requiring my parents to co-sign for me on stuff. I tried to get a simple card, like from a gas station but no one would give me a credit card because I had no credit history.
Finally I got an offer in the mail that gave me a card with a limit of $500 on it (with my parents as co-signers). Problem solved, I thought.
I was absolutely responsible with the card, always paying it off every month and never even approaching the limit. Then after about a year and a half I started wanting to make some bigger purchases, like a nice Tempurpedic bed for about $1,500. There was a nice deal on it where I didn't have to pay interest on it for several months and with my income I could easily pay it off in time. But for some reason I couldn't get approved for the loan. I still had to have my parents co-sign for me. :-( Thankfully (for them and me) I was responsible with my money so they were willing to do that.
Anyway, eventually I wanted to be free from the card my parents co-signed and so I got a new card with a lower limit ($300) and NO annual fee. I had that one for several years and every so often they raised my limit. Well, about two and a half years ago I got to a point where there was one month in which I could not pay off the entire balance. I had let my self-control on my spending slip a little. Long story somewhat shortened, I never have gotten that balance back down to zero in all these past two and a half years. In fact, my limit is up to somewhere around $12,500. I managed to get myself in about $8,000 debt in just two years, and those interest payments are a killer!
Over the past few months I've canceled the card, gotten new ones with balance transfer deals, and am working my debt back down to nothingness. My plan from here on out is to never ever use a credit card again. I'll stick with debit. Spend money the way it was meant to be spent: Pay with what you have, not what you might have eventually.
I personally think the best advice anyone can give you is to not get a credit card. It's best to just save up your money and have interest work for you instead of against you. There are only a couple things really worth going into debt for in my opinion, one is a (modest) house, the other is an education. And by education I mean paying for the classes and books and supplies. Not taking out a student loan to pay for your college lifestyle (car, clothes, technology, etc). Everything else should be paid with money you already have.