First, you need two laptops, or a desktop and a laptop.
Have Combat Arms opened on both, different account of course.
Now, for the steps.
1. Purchase a sniper rifle.
2. Make a game of elimination 140 kills, oil rig.
3. Have both accounts in that game (Game must be public.)
4. Position your main at the sink where most of the snipers go.
5. Position your alt at the stairs where your main has a good view of the stairs.
6. Kill your alt.
Just keep doing that over and over in one game. People will get suspicious which is why you must multi task and play on both, don't play on the alt to much though, when the alt gets like 10 deaths, leave the game and come back. OR just type saying you're a noob, if they want to kick you complain how you're just trying to learn the game and they aren't letting you.
I have gone 30-6 in games, remember don't always stay at the sink and repeatedly do this, you can also use your alt to see where the enemy is.