Ranger Tactics
The Ranger buddy: All Rangers should "buddy up" with another Ranger, and stick by them no matter what. Two pairs of eyes are better than one, covering each other, putting more fire onto the enemy, are all advantages to this system. The buddy team has a leader, starting with the higher ranked Ranger, the follower acts as a "wingman", covering the leader's back. If the leader is killed, then the surviving member becomes the leader, and the respawned buddy becomes the follower, and should make every effort to join up.
Keep your weapon up: Never point your weapon at the ground or in the air. Always aim at the most likely place where an enemy might pop up. That split second it takes to move your weapon up, might make the difference between life and death. Imagine that your weapon sights are pulling you forward, and you should be ok.
Have a destination: Don't just run in the direction of the enemy, choose a good postition and go there. Move from position to position, carefully observing the area before moving.
Use your grenades: Many times I've seen Rangers getting killed, while carrying their full load of grenades. Always look for opportunities to use them, don't get fixated on just using your main weapon. A good system is having a Ranger buddy cover you while you use up your grenades, then you cover him while he uses his.
Hit the dirt: Lying prone has many advantages, making you a smaller target, harder to see, and allowing much improved accuracy when firing your weapon. Even a tuft of grass can provide concealment when you're prone. If you're moving and come under fire, hitting the dirt will often save your life, keep your finger on the "x" key when moving so you can instantly fall prone. If you see a target at medium or long distance, fall prone before taking the shot, and you'll have a much better chance at a kill, and much less chance of getting killed if you miss. The dirt is your friend!