Halo 3

A really easy way to get this achievement is to play on guardian and camp in the yellow room with the lift. People will come up the lift and just stick them as they come up. Another way is if you are lucky enough to get swords on guardian play that. Grab some stickies and just wait for an enemy, have them come close and do a suicide run by sticking them instead of using your sword. Though this may take a few tries so don't be discouraged if you don't get it on your first go. Good Luck

Another easy way to get this without boosting is on a map that includes a sword spawn.(Construct,The Pit) ; or as mentioned an actual game of swords. Just aim to stick the guy with the sword, don't worry about being skewered. Just rinse and repeat.
I personally got this on The Pit. I went to the area underneath the sword spawn grabbed the sticky grenades, grabbed the overshield then went up to the sword.
I got lucky because some guy kept going for the sword everytime. So I just stuck him, he skewered me, then we did it all again. Most people who go for the sword on this map camp at the sword waiting for someone to come past. Use this to your advantage and stick them just as they think they have you.

Not really a solution, more of a suggestion for those who don't/can't boost:

Snowbound:
- Grab the stickies from the top of either building near the explosive barrels and head down into the underground tunnels. Use the shield doors to your advantage, popping through to stick then dive back. Just watch out for people with maulers down there.

Alternatively, play crazy king. You'd be surprised how many people stand still facing away from you ;-)

Tip for Boosters!

this is not a solution for the achievement, but for what comes after... (don't hate me for it, it's just to help)

If you managed to get it with the help of the Language-Trick, you'll probably have noticed that the name and description of the achievement is not English (or whatever).
To solve this you need to do the following for pre-NXE:
1. Go to the Xbox-dashboard
2. Navigate to the "Marketplace" blade
3. Press "X" to Sign Out, confirm it with Yes
4. Go to "Recover Account"
5. Enter your Gamertag and Continue
6. Put in your NET password and ID and continue
7. Wait for it to recover and check your English Achievements

for NXE:
1. Go to the Xbox-Dashboard
2. Press the Xbox-guide button
3. Press "X" to Sign Out, confirm with "Yes, sign out"
4. Click the "Recover Gamertag" button, and again.
5. Confirm to exit your current session with "Yes"
6. Enter your Gamertag and Continue
7. Enter your Live ID and your password and Sign In
8. Accept the Xbox LIVE Terms of Use and Privacy Statement
9. Wait until your profile is downloaded and check your English Achievements

The solution is not invented by me, although I wrote down the NXE version with the help of the following webpage: http://www.myxboxspot.com/forums/halo-3-glitches/1387-how-ch...
The pre-NXE solution is a retyped and shortened version of the idea that can be found on the same webpage, I have copied it because I wanted to spread the word about this solution.

Despite being skill level 36, I was able to get this achievement relatively easily on the map Narrows, with the game type Crazy King. There are plenty of plasma 'nades lying around, and the map is relatively close quarter with relatively few large open areas (the notable exceptions being the top of the bridge, and the area underneath it where the rocket launcher spawns. Anyway, try to avoid said open areas (unless a hill spawns there, but be careful), and use the grav lift to get from one side of the map of the other. Try and find people fighting it out for the hill, or wandering around in the small, narrow, enclosed areas. If the people are 'pros,' then they will definitely be jumping out of the way, so make sure your 'nades count. If you run out of 'nades, then try and get out of the combat and find some more. Respawn time is time wasted that you could be using to get grenade sticks.

I can confirm that the sticks have to be in the same round - it took me a couple of tries, but there's only one foolproof method for this: Suicide run at opponents and get the stick (plasma or spike grenade). I got this one playing Lone Wolf Slayer on Pitfall - plenty of grenades spawning around the place. As soon as you respawn, run around and collect sticky grenades before you look for a fight. Good luck!

Credits: CaliforniaHurBoy