How to maximize your efficiency from the ground up:
1) Take 1 or up to 4 seconds when respawning to get an overview of where you are and where your enemies/friends are
2) Decide what you do (join team, flank, hunt on sight, rush), dont just run headlessly into the map
3) Pick off the easy frags while passing high frequency routes by being smart with stealth and nanovision (quick toggle of nanovision is very helpful and minimizes energy drain)
4) Cover is essential, when shooting someone block at least one of your sides or reduce visibility by crouching etc. Practice a hit and run style if appropriate, balance it with retrieving dog tags when your energy is up again
5) Exploit your strengths, close quarter, sniping, medium distance, stalking, favourite weapon etc. all is fair except camping
6) Align yourself whenever possible to map geometry and enemy movement/routes, this is risky but if surprise is on your side, increases your accuracy immensely, especially in online play where ping induced prediction/aim compensation plays a role
7) Depending on the gamemode, safety lies in numbers, want to kill more and die less? Have someone protect your back.
8) Be disciplined and focused, dont run around with an empty mag, use stealth + voyage time to reload, be aggressive but not greedy for kills or dog tags, always, always, always aim where your next enemy is most likely to pop up, no matter where you're walking, this shaves half a second of your reaction time.
Good tips to those looking for some advice