I hereby typing this because I've read quite a number of complains stating that the game is too "difficult". The last time I've tried this technique, it'd gotten me to level 54 with ease. Hence I believe that this guide will be more than sufficient for all the casual gamers out there to last a bit longer.
The red dot is where your shots will most likely hit. Keep in mind that this game has bullet spread -- the shots may deviate away from the sights -- and it increases in proportion with the number of consecutive shots. So if you're in a trigger-happy mood and hold down the fire button, the first 3 shots will land within close proximity of each other while the remaining shots will fly all over the place. So its recommended that you perform short-quick burst or switch to semi auto ("F" button).
Here's my recommended built for this game:
Select the Glock as your starting weapon. The Glock is no doubt the best pistols among the three. Reason being that its as accurate (if not more) as the Kimber and its the only starting pistol that can be upgraded with extended magazines.
Level 1: Either purchase the secondary pouch or do not puchase anything at all (to save up cash).
Level 2: You should have sufficient cash to purchase the extended magazines for Glock. Buy and equip it.
-This should last you for quite awhile. Use the Glock with extended mags to save up for the big thing -- AK-47 (you should be able to get it by level 8). Purchase the grip and sling for the AK-47. Other attachments are not recommended as they just provide cosmetic differences.
-Purchase Primary Pouch, Heavy Belt Tier & Heavy Vest Tier.
-The remaining cash will be used to repair the Blackhawk or to purchase the A10. (to repair the Blackhawk, drag the slider towards the right and click "buy"
-Targer priority: 1. Always aim for the RPG soldier first! For they're the ones that'll cause a lot of damage. 2. Technicals (aim for the fuel tanks)
level 10+: there will be 1 technical for each round. There's no need to call in the A10. Just shoot the gas tank and watch it explode.
level 20+: 2 technicals. If you have good aim, there's no need to call in the A10 either. However, if you really feel that there's a need to, call in the A10 the moment you sense that you're in trouble. There's a delay before the A10 arrives. So you're on your own within that time frame.
level 30+, 40+, 50+ etc: 3, 4, & 5 technicals respectively. Its pretty compulsory to call in an A10 every round if you want to survive. (its recommended you call in the air support when there's at least 2 technicals in the screen).
Well, that's all I could cover so far. This is my first guide so please do go easy on me. =[
Glock. The ability to increase mag size from 12 to 30 gives it a major advantage over other starting pistols. Also, its just as accurate as the Kimber. =]
On the other hand...
UGH! I failed at wave 59.... AGAIN! I need help getting pass that level. >_<
Start with the Kimber, and buy the laser attachment for it. Here's the interesting part: if you have firefox, zoom in by holding Ctrl+Scroll(up). This will give you an amazing advantage.
Buy a Delta sniper only until wave 10, and save up to buy the G3. Get the attachments for it (obviously), buying whatever pouches your budget can afford. Prime a grenade at the beginning of each stage, and use an A10 as soon as the first EOD Suit comes out. This will ready the air strike for when the truck comes in.
Also, for the trucks, it is better to wait for them to stop and begin shooting, because they can be destroyed by one well-placed shot, rather than diverting your attention while trying to shoot the small gas tank on a moving vehicle.
Uhh... well, I got to level 54, but I'm using my laptop's pad as a mouse, so I'm sure that I could get a lot further...
Well, that's a pretty subjective matter. If you prefer accuracy, pick the Kimber. If you want spammability, get Glock upgrade extended mags for it (Kimber is un-spammable =[). I don't know the actual values, but it appears that both the Kimber and Glock are equal in terms of damage.
For me, I prefer the Glock because I don't have to reload as often as the Kimber after I upgraded the mag size. And since the Glock's extended mag carries 30 rounds instead of 12, you'll naturally have another 30x5 bullets in your pocket compared to 12x5 for the Kimber.
The Kimber is more powerful than the Glock, which comes into play if the spread is a bit annoying for you. Quite frankly the pistols are worthless once you become able to buy the AK; the less money you waste on the pistol, the better. If you're that inaccurate to waste all of your mags shooting infantry, just give up.