Don't in rush when in battle. It's better to let everyone before you and get into the heat of battle a bit later. Many will already be with low health and easier to take down.

Always check out the mission requirements so you know you can complete it. It is requirement you need to match to get it done and not necessarily to kill everyone.

Always move and strife... we need not to emphasize this. Though it's difficult to move and aim in the game, do it anyway.

As in most shooting games find the best weapon for you. You can try them all in training mode and see which one fits you best.

Assault weapons may be best fit in this game since they do a lot of damage and have great overall stats but with small clip size.

Remember to reload and take cover when under heavy fire.

Upgrade your favorite weapon when ever you can that can give you the necessary edge in battle.