How to change player nametag color.

I am on 1.8. I want to change player's nametag color. I don't want to use packets. I'll use any other method. I have tried scoreboard but it does not seem to work:

Code:

[SYNTAX:JAVA]if (scoreboard.getTeam(p.getName()) == null);
                            {
                                scoreboard.registerNewTeam(p.getName());
                                scoreboard.getTeam(p.getName()).addPlayer(p);;
                            }
                            scoreboard.getTeam(p.getName()).setPrefix("§4");

The color is just white.