I hear that playing at least an hour or two each and every day, and also reviewing your replays, will help you get better.
This guy, BBKDRAGOON, puts up videos with really sound advice. I love his videos. Look for efficient practice, what to look for in a replay, and maybe his beginners guide if you want. --- Proud supporter of the Halo 4 GameFAQs board. Yes, even Rageface.