Greetings Mechwarriors!
I would like to share some of the stuff i've learned since i started playing the game (around the end of June).
Adjust your settings. Disable cockpit glass, its useless; adjust your FOV, so you can see more from your cockpit; Reduce your mouse sensitivity at around .2, this will help your keep on target, very useful for lasers.
Reverse movement. Turning backwards is MUCH faster than turning forward; if you need to make quick turns or shoot that annoying light mech that's running around you, hit reverse when you are turning; for maximum effectiveness, twist your torso the same direction you are turning.
Stay together with your team, but keep your distance from your teammates, try to keep a minimum distance of 30m, this way you are less prone to cause team damage and blocking your team's movement.
DON'T chase the lights, just don't.
If you are having problems with torso twisting to avoid damage, try disabling armlock, it will require less movement from your mouse to twist your torso.
Focus fire, if you see one of your big boys shooting at something, then fire at the same thing he's firing and it will go down faster.
IF you are going to run a NASCAR, please, for the love of god, don't leave your assaults behind, the team will suffer greatly.
If you bring an Assault LRM boat (please DON'T), don't engage your targets at long distances; due to their velocity, LRM's are more effective when you shoot them at around 400-500m from your target. And please, stay together with your team and share some armor.
I'm still a bit mediocre and have a lot to learn, but i'm sure some of this stuff can be helpful to brand new players.
Thanks for reading and good hunting!