haha I'm sure your a great player your just getting frustrated.
Remember this isn't Halo 3. You could engage multiple targets in Halo 3 and if things got touch just duck out of battle. With this game the DMR is so much more effective than the BR at long range that even if an enemy sees you from across the map he can still get shots on you leading to you dying much quicker than you anticipated.
Always be aware of all the angles you will be vulnerable from when you get into a fight, have an escape plan ready if needed and always move with your teammates or at least in a position in which you can get help from them if you need it. Also remember not to push in as much or at least more cautiously, unlike in Halo 3 grenades in this game can seriously injure you, especially if you don't have full health or shield.
Pretty basic stuff but essential to master.
The definitive evidence that video games turn people into mass murderers
