Put all of your players going the same way in strategies and you will most likely win.
Easy "Predator" achievement
Go to "Multiplayer" and "Public Match". Create your own game. Set the maximum number of players to 14 and reserved slots to 13. Set the game to first 5 out of 9. Place bot players on the opposite team and be the only player on yours. Start a match on the Buffalo Field. Eliminate as many players as possible, then let the last person shoot you. When they have won four, stay put and win the last five by eliminating all the players. Rush straight to the right and the opposite team will line up on the opposite end. Keep shooting them and making new games with the same rules until you get the achievement.
Tippmann X-7 AK-47 Scenario paintball marker
Go to Career mode. Select "Field Gear", then "Enter Cheat Code". Enter Up, Up, Right, Right, Down, Down, Left, Left as a code.