There are two ways you can get this achievement: playing legit or boosting. I believe these are the best ways to do both.
First of all, I fully recommend doing this achievement legit because boosting can be more troublesome and time-consuming than it is worth. However, if you find getting the wins to be too difficult, here is what you should do:
1) Get a party of a minimum of 8 to a maximum of 12.
2) Break into two teams split down the middle. Depending on your numbers this is what you should do, 4v4: Team Anarchy, 5v5 Team Objective, 6v6 Siege.
3) Have the two teams search for each other in whatever playlist. (You'll have more success if one team creates a new game lobby and the other team searches right when that happens) Back out whenever other players start to join in before you get locked into a game. If you keep finding the same randoms, then don't keep joining because your chances of getting locked into a lobby with them will just increase and you'll either have to dashboard or wait til the game starts to quit out.
4) Once you have both teams in a game together, have one team quit out and the remaining team will get an instant win.
5) Rinse and repeat.
RFG has some problems with host migration right at the start of games so don't have everyone on the team quit all at once because it could boot everyone out of the game with nobody getting a victory. Instead, pick an order in which everyone should quit. Also, one player on the team will tend to always be the primary choice for host. It'll become obvious who it is because everyone will get kicked the second that guy quits so when you find out who it is, make sure that guy quits last on the team.
If the team are uneven go with the following setup: 5v4 should play Team Obj, 6v5 plays Siege. Once you're about to get into a game just have all the players ready up (press Start) and you hopefully can close the lobby out to randoms before the game starts.
If you do end up getting randoms in your game while both teams are present, then just have the team without the random quit out. Unfortunately, the randoms don't always quit even when the whole rest of his/her team leaves and you could be stuck playing for 10 minutes.
(Update: Please keep in my that the methods here are based on the multiplayer climate in 2010. My guess is that the community has probably shrunk significantly over the last 2 years so your results may vary.)
I find this to be the best method to get the achievement the old-fashioned way. Not only will you win often, but you'll also get kills and XP towards other achievements. Plus, its just good ol' fun.
1) Get together a team of 5.
2) Play the Team Objective playlist. I've chosen objective because half the RFG community doesn't know how to play the objectives well or at all. If you have a full team playing the objective it is really hard to get beaten even if you're not the best at getting kills. I don't recommend Siege because the games are twice as long.
3) When the option appears to ready up, do it as quickly as possible and you can usually make it so that it is always a 5v4 so you already have the initial advantage.
4) Win. Here's what I recommend:
Team Objective has three gametypes: Capture the Flag, Demolition, Damage Control.
Capture the Flag - This is not only the easiest one to win, but it is also the quickest. Have at least one team member play defense (knowing where proximity mines are located helps a ton). The rest run the enemy flag. Try to have one player hang out at the enemy flag spawn to get a quick grab after you score. These games can be finished in two minutes if you're good enough.
Demolition - This will probably be the longest gametype to win, but it isn't hard. Most Demolition maps have one or two structures that can be taken down for hundreds of points (Ex. Fall Factor's bridge, any building with multiple stories, etc.). Instead of running around breaking everything in sight, bring that primary structure down and have your teammates rebuild it, but rebuild it in such a way that it can be taken down again easily. If it is a two story building for example, just repair the stairs on the first floor and only repair the second floor. Once that is mostly rebuilt, a couple hammer swings can bring the building down again. Rinse and repeat. The destroyer should take advantage of certain weapons and backpacks: singularity bombs, remote charges, nano rifle, thermobaric rockets, Rhino, Firepower (esp. with the hammer), Thrust, and Tremor. Always have at least one teammate watching the destroyer while the rest go after the enemy. Also, if the enemy destroyer gets close to taking down a building, send your destroyer over and steal the finishing blow to snag some easy points. Remember, if you don't want to be the destroyer, hitting the Y button will pass it to your closest teammmate.
Damage Control - An interesting take on Territories, if you're having a problem dominating all three points, just take two of them and play defense. Too many teams get into the habit of just running around the map in circles, repairing, destorying, repairing, and destroying. That is not how to win. Again, knowledge of proximity mines is key. My favorite tactic is to grab the jetpack and nano rifle/rocket launcher, then fly around taking out control points from afar. It'll keep the enemy occupied with repairing the point while your team swoops in for the kill.
If you don't have a team of five then keep playing and partying up with people that you meet along the way. Everyone likes winning so most people are usually ready to join you.
Using these methods, I've gone on winning streaks that lasted 30-40 games over just a few hours. Since the community is small, people will start recognizing your team and quit out at the beginning of games, making it even easier.
Also, keep in mind there might still be people out there that play this game and are seriously good. You'll know when you see entire teams of people with the red bars with black stripes. I came across one or two teams like that and they wiped the floor with us. You won't see this too often, but I would say just be wary of them.
Sidenote: Hitting people with an ostrich can be terribly demoralizing. Try it sometime!
Some people have been unlocking this achievement at 249 wins or earlier. If so, then good for you.
If you have any suggestions on how to make this solution better, please drop me a line in the comments. Good luck!