I'm going to keep this guide short and simple as there are plenty of other guides explaining things better anyways.
Now, you shouldn't really worry too much about this achievement as you will most likely get this along the way while trying to knock out the other achievements. With that said, I think I've found a cheap, easy and quite useful tank/guide to use if you're going strictly for kills.
This my friends is the British Tier II Artillery tank called the Loyd Gun Carriage (Loyd GC). I heard about this tank while going for the "For Her Majesty" achievement which is for getting 4 kills in 1 match. It's not expensive to buy, so anybody should be able to purchase it quite quickly.
I've been in 3 games already and each game I've scored at least 3 kills and each time I hit an enemy it was an instant death for them. I didn't buy any upgrades yet but right now, it's a 1 shot kill tank. You may need to understand how to use the artillery a little before using it, but it's a very good tank. Learn how to lead your shot and shoot ahead of an enemy if they're moving. Also be patient and wait for the green circle to center in on your target and then fire. You shot will be pretty accurate and you should hit your target most of the time.
For starters, when a match begins, find a location where you have an open view of where the enemy tanks should be going to. You may have to move up a little bit if it's a big map. Don't be afraid to move around if you see the enemy tanks are elsewhere and you need a better shot. Be patient and kills will come.
If the green line is red, it means there is something blocking the way in between you and your target. There isn't much you can do about this except for either find a different location or wait for them to get into open view for you to shoot at.
If the green circle dots are focusing in but not over the tank, it means you need to turn your tank and face the enemies. You can do this while aimed in so it's not a big deal.
If the line is white, it means you are out of range of the target. You will have to move up closer to the fight or wait for them to move closer to you.
If the enemies start shooting at or starts rushing you, there's not much luck you will survive unless you have a tank who is protecting you. The best advice I can give about clearing out close ranged tanks is to retreat and hide somewhere safe. Do not come out and be patient, as most likely the enemy team will try to rush you anyways. If they start taking the flag, ignore it as you will probably lose anyways, no point in dying. Find somewhere that they cannot get you from behind and wait for them to come into view. And now shoot them without aiming and hope you don't miss. You can turn the auto aim on in the options menu and then use it by pressing RB while hip firing. This is called shotgunning and has been known to work quite well when in tight situations. I've seen artillery take out 3 tanks before because the enemy team was impatient and rushed the artillery. It's not always going to work, but it's pretty much all you have left.