Halo 3 / Call of duty 4 gaming

I have been playing Halo since the first incarnation, but never played online (Xbox Live) until Halo 3.  When I started playing online almost 2 years ago (during the Halo 3 Alpha), I realized how bad I am compared to other players out there.  Once it went live, I realized that I TOTALLY SUCKED compared to other people out there.  Since then, I have played enough that I have gotten better at sniping, throwing grenades and using my battle rifle.  However, I am still trying to figure out how to constantly jump and still shoot accurately, jump and snipe accurately and shoot / snipe accurately while being shot at.

For those of you out there who also play Halo 3 online and are willing to share some tips and tricks with me (and a few other close friends), please feel free to comment with those on my blog.  :-)

To continue this thread, I finally caved in and bought my son Call of Duty 4 and he is now playing that game online.  He let me play a few times for a few minutes, but I REALLY REALLY SUCKED at that game.  I have a very hard time seeing the opponent, let alone shoot them.  If it took me 2 years to just get semi decent at Halo 3, how long will it take me to get semi decent at COD4?  Once again, any tips and tricks?

Or, is it true that I'm just too old to really learn and should just accept that I'm as good as I'll get?  That happens to be my son's opinion.  How does everyone else "deal" with this scenario? 

Harold Wong