i currently have ONE credit card. i've only had one my entire adult life. as long as you are responsible, don't go over your limit without a loan first or other reason like a home, you should be fine, and it will help build up your credit score. as long as you have a job and can pay your credit card, most, if not all you can set up so it pays automatically before each bill is due. so it does it for you, but it's still good to look at it once in a while to make sure it is what you're charging on the card, and no one else has your info.
look for one with no annual fee, and maybe even have one of your parents cosign with you to get a good rate. then overtime you can take it over yourself as you prove you can be responsible. one's with annual fees usually come with perks for flying and other rewards. you can read sites that compares credit cards and their benefits and possible late payment penalties.
if you're young in general, your score is low because you have no credit history. but it builds up over time as you pay off your credit card and your other debts. then you just gotta keep it there for better rates in the future for loans when you get a car, home, or other big purchases.