I actually disagree with not picking aero until later on. Air assets are almost a completely different game to ground assets and even VTOLs are pretty different to aeros. Leave planes till later and the frustration of being a noob all over again can land you back on the ground(me so funneh) in a hurry. Plus, we are sorely in need of decent dog-fighters
General tips are use team chat to ask for help/questions and coordinate with the team, experiment with as many different assets as you can/want/like, play around with active and passive radar, practice aiming and spreading damage, pay attention to equipment besides weapons, look up stuff in the wiki(though some parts are out of date after the huge 0.7.x updates) and stick with the game.
Most people suicide rush at first, play more carefully over time and then start figuring out going balls to the walls, retreating and playing peek-a-boo with potshots. If you don't have fun while playing this ain't gonna happen, though, and the learning curve is pretty brutal at the beginning. It does get better over time, just make sure you don't burn yourself out. I started playing MW:LL after a long hiatus from videogames in general and, for the first month, playing more than one game every couple of days made me feel very, very frustrated.
If you take some time looking through the actionmapper you'll see most of the controls. Default eject is F(you now need to press it twice in a small time frame since people kept ejecting by accident while trying to turn right). I think you need to set free reticle yourself. A lot of people seem to unbind the crappy voice chat and use left alt. You can play with free reticle on toggle and switch mode, and using cl_free_reticle_independent on 1 or 0 (it's a console command that changes the free-reticle behavior). Unfortunately you need to get out of the game to configure controls. I agree that the new free reticle has its quirks and was very frustrating at first, but it seems better than the old one now that I'm getting used to it.
Welcome! Have fun and you'll figure stuff out over time.