It's often said that a man can be judged by who he surrounds himself with. Who you surround yourself with can often determine what type of person you become. Proverbs 13:20 says, "He who walks with the wise grows wise, but a companion of fools suffers harm." If you pick wise friends, Godly friends, mature friends, intelligent friends, then you will grow in wisdom, Godliness, maturity, and intelligence. In the same way, if you pick foolish friends, immature friends, Godless friends, perverse friends, then you will grow in foolishness, immaturity, Godlessness, and perversity. Proverbs 22:24-25 says, "Do not make friends with a hot-tempered person, do not associate with one easily angered, or you may learn their ways and get yourself ensnared." See that? Don't associate with a hot-tempered man or one who is easily angered, because if you do, you'll become like them. Who you choose as friends greatly impacts who you will become.
The Bible tells us to pick and choose our friends wisely. Proverbs 12:26 says, "A righteous man is cautious in friendship, but the way of the wicked leads them astray." To me, that says it isn't wise to become best friends with someone overnight. Unfortunately, I know from experience that friendships that start too fast end too fast. But the relationships that take time to mature usually end up to be good friendships.
As Christians, our standards for our friends should be higher than the world's standards. In Psalm 101:4-6, King David wrote, "The perverse of heart shall be far from me; I will have nothing to do with what is evil. Whoever slanders their neighbor in secret, I will put to silence; whoever has haughty eyes and a proud heart, I will not tolerate. My eyes will be on the faithful in the land, that they may dwell with me; the one whose walk is blameless will minister to me." David started off by saying that he would have nothing to do with perverse men, or with gossipers, the prideful, or the arrogant. Those are the people he wouldn't surround himself with. But the faithful and blameless? Those are who he would surround himself with. David had high standards; he knew to surround himself with those who would help him grow, who would build him up.