To choose friends, you must be careful. do not choose the wrong friend, because friends are one of the determinants of your front mass. if you have a bad friend, chances are that your front mass will be bad. if you have a good friend, most likely your front mass will be good. this depends on how much influence you have on your friends.
I will tell you, how the nature of people who are not good to be made friends. the first is he wants to look good but in a way to speak ill of others. instead he does good. but he vilifies others. do not make people like this as a friend.
secondly, if there are people who want to be great by bringing others down, that's not good for friends. for example he wants to move up a position in a company. but to get promoted, he vilifies others, he commits slander, so that the position he wants can be achieved.
other than that people who feel great and feel always right, he is not good for you to be friends.