Bodycount

This was the last achievement I needed and it was some what of a pain in the buttocks. Once you get in a game it's not too bad but I've been in a full lobby, everyone ready and the game will not start, also people quit when they are losing all the time.
Sometimes when people quit it will say you are the match winner but not 100% sure if it counts them all the time as I counted 19 wins before I got the achievement and I almost gave up.

If you have a friend that has the game then boost. Just go into single deathmatch and one person keep running to where the other is hiding untill they get the 15 kills, take it in turns. I saw two people doing this in a deathmatch I was in so I quit cos there was no way I was gonna win lol

If like me you were on your own, I chose mainly team deathmatch and hoped to have a couple of decent players on your team (people killing with headshots using the pistol, very annoying when your against them).
Mines and grenades are your best friend. Find a good doorway to put the mines or somewhere that gets a lot of traffic.
Once you have a kill quickly gather the orbs from the body, when your meter on the left is full go to one of the many weapon points (marked as a red dot on the map) swap one of your weapons, which ever you don't use and you will get more mines and grenades, then the deathmatch will get easier and easier as people will constantly go over them and you can go back and get more

When Boosting there is a quick and easy way to win a Deathmatch by reaching 15 kills, and if all goes well it should take 5 or so minutes, maybe a little less per match. Overall per person it should take about an hour or so assuming you do 10 Deathmatches, but I would recommend you make one of the 10 Deathmatches a Team Deathmatch to make progress on this achievement and get that one out of the way as well.

NB: Rather than simply direct users to another Guide, I have replicated the below from my Guide for winning a Deathmatch.

When in the lobby you'll want to Veto Map until "Militarised Compound" comes up as the map. This map is small and has some structures on the outer edges but the main building in the middle of the map is important. There is a corridor that runs between the Eastern and Western sides of the main building, with a doorway at each end providing a clear line of sight/fire from one end to other. Think of these as East Door and West Door. All assuming the white marker on radar is North.

The Winner (going for wins) and the Opponent (cannon fodder) should meet inside the corridor for the first kill (Winner killing Opponent). After which the Winner should blow up (double tap cn_RB for contact grenade) the room just North-West of the East Door to gather a lot of Intel, alternatively killing the Opponent 3 or so times total to gather enough Intel. There are likely other rooms to blow up for Intel.

The Winner will want to use the TAVOR rifle that is available for 12 Intel from the drop-pod South-West from the West Door. This gun has fine accuracy when aiming down sights with cn_LT allowing good shooting down the length of the corridor. A full pull of the trigger with cn_RT should fire a three shot burst doing enough damage to kill quick. Otherwise each quick tap will fire a single bullet.
Once the Winner has the TAVOR they should position themselves outside West Door behind the short barricade so their line of sight/fire runs down the corridor.

Now the Opponent after this should continue to respawn and place themselves in the line of sight/fire giving the Winner a clear shot without needing to move their aim much. As long as the Opponent places themselves anywhere directly between the short barricade outside the West Door and the drop-pod outside the East Door, the Winner should get a clear shot. The spawns are all over the place but shouldn't be too hard to get used to, or generally using the radar to head in the right direction. So without prior knowledge of the map it may take longer than 5 minutes the first time.