Hey I'm a prestige master in Black ops 2 and i have all diamod guns also igot the peacekeeper gold in one day and everyone was asking how I did it so I'm gonna give you a few tips.

1. Always aim for the head. If you are one of those people who say oh ill get it eventually its gonna be awhile. But if you go for headshots you will be surprised how fast you will get them.

2. Play the right game type. Obviously your not going to get very many headshots in search. I recommend playing chaos moshpit because it has short range maps and you can get a high amounts of kills In a game.

3. Once done with headshots I immediately take off all perks and attachments and go for bloodthirsties.
Most often blood thirsties are the hardest and last thing you will unlock.

4. What I do is rush or play until I get 3-4 kills then I play it safe to get the last one. I'm not saying I camp but you could camp if that's more your style

5. Kills with no perks and no attachments are easy enough to get if you need long shots I normally find out a spot in a map where I can get them and then stick around in that area. Lastly double kills and revenge medals you can get fairly easily just by playing.

Challenges for each weapon class

Primaries

Assault rifles: 10 long shots- 150 kills with no attachments or perks: 20 double kills: 10 bloodthirsties

Snipers: 50 kills with no attachments or perks- 10 long shots - 10 blood thirsties - 5 double kills.

Submachine guns: 150 kills no attachments or perks - 20 double kills - 30 revenge kills - 10 blood thirsties.

Shotguns: 30 revenge - 50 kills no perks or attachments - 5 double kills - 10 blood thirsties

Light machine guns: 10 long shots - 150 kills no perks or attachments - 20 double kills - 10 bloodthirsties

Assault shield: 1000 score from blocking enemy fire - 25 hatchet kills while holding the assault shield - get 25 shield bash medals on the person who is shooting at your shield -25 kills no perks - 25 kills with no weapons equipped.

Secondaries
Pistols: 30 revenge medals - 150 kills no perks or attachments - 20 doublekills - 10 bloodthirsties.

Smaw: 10 impact kills - destroy 5 aircraft in 1 game - 1 car kill - 5 double kills - destroy 1 dragon fire
RPG: 10 impact kills - destroy 1 aircraft - 1 car kill- 5 double kills -1 triple kill (MEDAL)
FHJ-18 AA: destroy 10 aircraft quickly as it enters the airspace - destroy 5 aircraft in a single game - destroy 2 aircraft back to back - destroy 10 player controlled score streaks - destroy 1 AGR

Ballistic Knife: 5 revenge medals - 25 melee kills - 25 kills with retrieved ballistic knife blades - 1 double kill - 2 bloodthirsties

Crossbow: 1 double kill - 5 revenge medals - 1 car kill - 1 bloodthirsty medal - get a kill with every round in a clip of your crossbow. (1 impact kill with tri bolt)

Combat knife: 10 backstabs - 5 survivor medals - 5 revenge medals - kill 5 enemies with their weapon after killing them with a combat knife - 5 bloodthirsty medals.

I hope you found this helpful.