I completely agree with the fact that you need to learn the maps,
including where the weapons are and where all of the shortcuts are.  If
you are playing a game of CTF (Capture the Flag) or Assualt, and you
don't know exactly where you are and where you need to go, then you need
to spend some more time exploring the maps.  There are quite a few sites
out there that will give you either text or video walkthroughs of the
maps... take advantage of these.  Also, communicate with your teamates
in each and every game.  There are some a.sholes out there, but
remember, for every mean arrogant gamer there are 15 more helpful ones.
 Ask for assistance, follow your teamates around the map to see what
routes they take.  You will discover the 'power' weapons much quicker
this way.  Dual-wielding is still key for close encounters unless you
have a shotgun or sword.  Battle Rifle is a tough weapon to master, but
once you do becomes one of the most dominant guns in the game.  If you
don't think you can snipe someone moving in irregular directions above
and behind obstacles, leave it to one of your other teamates.  If you
still have questions, surf the bungie.net forums or halo.bungie.org to
get some more general tips and tricks on the strategies of Halo2 Live!
Above all, COMMUNICATE with your fellow XBOX live brothers and practice
your a.s off.  After a few rounds on each map, you will definitely be
able to hold your own.  My gamertag is:  IB768     Anyone on here feel
free to send me a message and let's rock out for a few games.  I always
like to meet fellow newsgroup folks.  Good luck!

Three head shots will kill a player easily.

You need to aim at the head only.  Pistol fire individual shots (not holding
the button down) a little bit slower than it's maximum fire rate.  If they
are moving sideways relative to you, you may need to fire in front of their
movements to connect, so you must listen to the damage confirmation to
figure out when you're leading far enough.  Any time they jump you now know
their movement pattern for the next 2 seconds and so should be able to get 2
clean shots in that both connect, 3 if you're lucky/good.  Make sure you'r
always, always always moving in a random pattern, nothing is easier than
getting headshots on a stationary target.

AR is useless for all but a few close-up scenarios.  Change it for the SG as
soon as possible which is much more effective in those same scenarios.

Use frag nades to assist your pistol battles.  Lay them down where he's
headed, they will either compliment your pistol attack and add damage, or,
if he sees them and goes the other direction, you know where he's running so
you should get a couple of good pistol shots in.  You can even use them some
times solely to direct him, knowing he will see them and go the other way,
to keep him where there is less cover or where a teammate can assist you.

If you try to run *me* over in a warthog, I better be out of frag nades or
very badly distracted.  Flipping hogs is *easy* and you can pistol the guy
to death before he hits the ground afterwards.

I'm assuming a normal pistol here, if it's a fast-repeat magnum pistol, fire
as fast as you can at the maximum fire rate, practice reaching but not
exceeding that rate.  All other advice is the same.

-Russ.