On Karkand as USMC Medic.
IMHO you need three things to get this badge:
1) Sneaky skills e.g. attack an enemy from the side or behind
2) UAV - to show you where the enemies are and which way an enemy is facing
3) Luck - that the enemy isn't using his minimap - that his team-mates haven't spotted you - that his commander hasn't spotted you - that his team isn't using UAV - that he isn't a noob-tubin bunny hopper that will jump backwards and blow you away when you are 2 feet away - that you don't get next to him and knife the wall instead.
Other tips:
- Use ladders (see my other post:
http://forums.bf2s.com/viewtopic.php?id=10403)
- Go as Sniper or Medic (not support!) as they both have long sprints. Snipers are hard to tell apart and medics can heal themselves.
- Learn to "Run - Jump and Prone" stab
- Stab people in the legs/feet
- Stay calm when using the Knife, although the enemy probably will usually cack his pants!
- Stop still before you stab someone
- Learn the effective distance of a knife - if you are too close you will hit the wall or ground behind the enemy
- assign the Knife to an easier to find key or mouse button. Mines Mouse Button 3
- don't run round with your knife out - if you meet an enemy at medium range - he will have killed you before you can switch back to your gun
- don't pull the knife out until you are near the enemy
- practice the above on single player...
Don't give up hope on this badge... I thought I'd never get enough knife kills - now, whenever I'm in a situation that combines 1+2+3 above I pull out the knife and go for it. I have 97 knife kills and will be going for my expert shortly