A good like-minded friend (who has solid beliefs in the Truth) is always a good thing for any Christian. I'm a rather introverted person so I naturally am only drawn to very few close companions. I'd say I have two that I'd call "close" but one I have to use good judgement around as they aren't Christian so don't always understand my reasoning for certain actions I might do. (For example I really liked a guy I used to work with, but he wasn't a Christian and being unequally yoked and working for a relationship like that could be dangerous for the both of us so I never really pursued it.) Something like that might not make sense to someone who doesn't half the same beliefs and thinks that if "said boy" was a good person he would be mindful of my beliefs. But that wouldn't have been fair to either of us. Likewise, my "other" close friend (whom I refer to as my sister as I have been "adopted" per say by her family) is a firm believe in the Truth and has helped me to grow and understand it. She helped keep me on a steady path in the right direction, fully understanding my trouble as it (unfortunately) seems to be common issue for young singles to be tempted by unbelievers whom they are attracted to. She encouraged me and kept me from making poor decisions that could have seriously messed me up (though she had experience with that particular issue as she had been dealt a bad hand with it).
Anywho, a good relationship with another Christian to help keep you accountable for your actions is very helpful.