The only way to build credit is to use credit wisely. I sometimes come across younger adults who want to purchase a home but don't have a credit score because they have decided that it's best not to have any credit cards or loans. They were under the impression that they were doing themselves a favour by not getting into debt. The truth is, you need a credit score to do a lot of things today like rent an apartment, or get a cell phone. Eventually you may want to purchase a house and it's very hard for a lender to assess your credit worthiness if you have no proven history of managing credit.
My best advice is to get a credit card and use it wisely. Pay it off, in full, every month. This way you are building credit but not paying outrageous interest charges. It's best to try to obtain a credit card as soon as you turn 18. This way you will have a strong credit profile by the time you want to purchase a home, and get approved for a mortgage. You are not doing yourself any favours by avoiding the use of credit altogether!