When I first started Battlefield 3 (2011), I seemed to have forgotten all the lessons of Battlefield 2 (2005) from some years back.
In the fury of battle, I would respawn at the wrong spots, I would stand and gaze at the situation at the wrong spots.
I was averaging a Kill Death ratio (K/D) of 2:14 or thereabouts.
In meeting engagements in a fire fight, I would find that the other player would always shoot faster and more accurately. This was, of course, also due to my lack of skill, slower reflexes, poorer hand-eye coordination and manual dexterity.
I had also played an engineer with the rocket launchers (SMAW and RPG-7) or the MANPAD (Stinger or Igla). With the use of anti-vehicular mines, I was able to amass a few kills without a firefight. Relatively few though.
For 73 hours, I had tried different approaches, from driving vehicles to laying mines. Eventually, I managed to find that I could aim pretty accurately with the M320 grenade launcher.
That was when I was able to amass kills. By the 102th hour, I had chalked up another 1000+ kills and restored my K/D ratio to 1.0. I had over 700 kills with the grenade launcher there. I was able to place grenades accurately at long range with the M320.
Now, my K/D ratio in games would range between 2:1 to 7:1, the latter ratio was not uncommon.
I am glad that I had persevered. My gun kills have also improved. I positioned well and not merely from ambush positions. While the preponderance of kills had come from the M320, I would still get assault rifles kills.