Halo 3 Achievement Stratagies?

[Courtland]

I'm in need of a website (or you guys) to tell me how to do some of the newer achievements (passed the old 49/49, I currently have 65/79) plus some of the older ones...
I need:
-Have fun respawning (Extermination on a mythic map)
-Save this film (Perfection on a mythic map)
-Killtacular (..on a mythic map)
-Post Mortem (Death from the grave x2 on orbital (seriously need help with this one))
-Two for one (Spartan Laser kill x2 in a ranked free for all playlist)
-and all the others that I can't currently get cause of the last three mythic maps not being released yet.

 

[jose h]

Well just wait n u will get them when they come out

 

[Platinum Ice]

Well checking on Bungie's forums is always a good idea
(http://www.bungie.net/, in case you didn't know)

For the Post Mortem, go into a place with several enemies clustered together with some Plasma Grenades and right before you die (It'll be a suicide mission), toss one at one of them. Worst case: You'll miss Best case: You'll hit them and they'll explode killing their companions as well. Keep in mind you can get anything in between.

For Two for One, try to aim for someone hijacking a vehicle. I'm having trouble with this one as well, so I don't have much other advice to give you, except always try to carry a 'Splaser with you.

For the other ones I can't help you; I'm trying to get those as well.

HOWEVER.

http://www.xbox360achievements.org/ offers guides for every achievement on any Xbox 360 game. That would be a great place to check.