I built my credit with a couple small student loans (2.5% interest FTW!!!) and a credit card used to buy food and gas that I've never carried $0.01 on in the years I've had it. When I applied for a $100,000 mortgage to buy my first house a year ago, they said my credit score averaged 730 (3 different scores) and that they would be more than happy to give me a 30 year mortgage at a 5.00% rate.
I pay extra on the mortgage every month. I've also been early or on time with every other bill (gas, electric, internet, phone, water, student loan payment) so I'm guessing my credit score has only gone up from where it was.
My advice to all you wanting to build credit:
1. Having good credit is helpful, but you shouldn't plan on using it. Debt is a nasty thing that should be avoided unless you can use the money to earn a better rate of return than the interest rate you're paying to carry the debt.
2. Borrowing money for something that's going to depreciate is a stupid proposition. Borrowing money for things that have a reasonable chance of appreciating (like a house or an education) makes sense because the appreciation in value offsets the interest you are paying to have the money ahead of time.
3. Given the above point, DON'T BORROW MONEY ON A DANG CAR!!!!! The car makers and dealers have been very successful at convincing the american people that borrowing money to buy a car is "normal", and that you "deserve" to drive something nice and new regardless of whether or not you actually have the money to buy that car.
My advice is to get whatever credit card you can, use it for everyday purchases, and pay it off each month. Student loans are also an excellent idea because they are usually very low interest and nearly impossible to be turned down for. Just keep it within reason. Borrowing $80,000 to get a degree that will earn you $30,000 a year is going to put you in a large hole for many years to come.