Know the character and history of someone before making him a friend. However, friendship does take investment. The best vitamin for acquiring a friend is B1. If one wants a person to be his friend, then he has to give the commitment and loyalty in order to get it in return. One must watch out for his friend's best interest and to be there for him.
Life is enriched by true friendship.
A true friend doubles the joy and halves the grief. Rather, you shall lift them up with him. You need not allow someone to take advantage of you just because you want to do kindness and he is lazy. It is important to understand the Torah's definition of what constitutes being taken advantage of. This is true even if he will never help you.