Ok, the easiest way of getting this achievement is on Capter 2-2.

What you'll need:
A good sniper
The Knife
Sheva WITHOUT a Sniper

After you go up the stairs leading into the building where Irving, he is taken away by the masked being (Jill) and you are left to try and snipe everybody below and then go down after them.

If you go to the windows on the right and move back a few steps the turret will not hit you, and you should be able to see only the head of the Majini on the turret, which you can then pick off with your sniper.

Kill every Majini down there except for the one in the back of a ute with the crossbow. He's really close to your position and is actually quite a good shot.

After he is the last one remaining, stand as close as you can to the window and weild your knife. Wait for him to shoot, and swing almost straight after. He can only see the top half of your body, so he can't aim at your feet to make it difficult. He'll aim at your upper body, where your knife is, so it's pretty hard to not hit the arrow.

The key is timing.

An easy way to get money early on in the game is to get up to chapter 2-1 and then replay the fiorst mission a few times. The reason for this is it is the easiest mission and has lots of Ammo and Healing items in it. Also when you kill the big guy with the Axe he drops and item woth $5000. Also if you are playing on Co-operative you both get this item so it is at least 5,00 each for an easy mission plus loads of ammo and healing items to boot. Your eally only need to use the handgun in this level too so you can get lots of rifle and shotgun ammo from dead enemies.

When you get the furnace key and unlick the door you are attacked by the second boss, which appears to be loads of tenticles araped round a deab body. Do not shoot at it yet as you will just waste ammo. Go back to the room where you get the key off the dead solder. Now knock over the cannister next to the door and stand just round the corner, when the boss walks over it he will consume it into himself. Now run into the furnace just behind you and he will follow, shoot the cannister when the boss is fully insode the room. Now run outside and turn on the furnace at the control panel, this will clost the doors to seal him inside and kill him. And that is boss 2 beat and you will have only used 1 bullet. Kepp in mind that Sheva will still fire at him so it is better for co-operative play as you can tell your friend not to shoot. Hope this helps.

If you need a lot of money quickly load the chapter were you have to battle all the lickers. Each one of them should drop a jewel. Then just quit the game and repeat as many times as needed. Or do the egg cloning glitch. Doing that glitch will give you even more money.

Have fun

Ok I recamend using a fully upgraded hydra shotgun with infinet and an infinet rocket launcher because that will get you through the game easily and it has enough power to easilly kill normal foes and the rocket can kill harder enamies like reapers (if you don't no what they are the bug things) and if you use that combo and play the 1st mission on amature you will almost never die unless you really mess up also doin that will help you rack up exchange points and gives you a pretty good amount of gold per runthrough

For the guy with the axe that kills the person you talk to about the black market deal, if you can't kill him, run past him as soon as he breaks the gate. If you run all the way down, and take two lefts, you should see the ramp where the guy with the microphone was, and after you get up there, jump onto another roof, the fat guy can't make it and he'll just patrol around until Captain Kirk rescues you and you'll complete the level.

If you want to get a ton of gold just repeat Chapter 2-1, 3-1, and 4-1 because they have alot of treasurs.

Having trouble killing that Majini with a rotten egg? Heres an easier way to do it, but you have to beat the game once or until you unlock the liquid nitrogen rounds for the grenade launcher (freezes enemies on contact). Anyways, start chapter 1-1 and make sure there are plenty of enemies around to distract Sheva, otherwise she'll shoot them before you get the chance to throw the egg =(. But as soon as you shoot an enemy with the nitrogen round, they'll be frozen...switch to the rotten egg and throw it at them, they should shatter into bits :D! And theres your egg on your face.
Happy Gaming- How Can I Assist You

Hate those enemies that attack you and you have to press a button to dodge? Low on ammo at the time? Reload then dodge... Whenever you think your going to dodge reload, if you time it right, not even a second after you reload the dodge conformation should appear, that's when you dodge. If you time it right you will dodge and have max ammo. If you miss you will take damage, but still have max ammo.

Hope this hint helps you survive longer.

This Faster reload trick can work just about anytime you would want it to... Refular reloading takes way too long and gives you the chance to be vulnerable... The basic one is while your standing still and open your menu. Highlight your weapon box, press X, highlight the weapon that the ammo combines with then press X again. If you have enough ammo your weapon should have max ammo. If not you will just have more ammo. If you've already mastered this technique then try this. Hate being surrounded and need to reload? If you have just about enough ammo left shoot the enemy in the legs, approach them and press X. As soon as you press X your character should perform some type of melee attack. Don't just look at your character be a big shot, while your character is doing the melee attack that's your chance to do the reload trick above. If you do it fast enough then as soon as your character is finished that's when you either decide to run then shoot, or unload on them...

Running out of time? Can't find anymore time?... Just melee your enemy to death. If you kill your enemy with a melee attack you will get 5 seconds of extra time. This might not seem like alot but after a couple melee kills in a row you will gradually gain lots of time and a high kill streak.

Hope these tricks help you survive longer...

Sometimes when you shoot rats they will dropp random amounts of money