Having now beaten the game on Hard, and going for the Superhuman Run next, I would like to emphasise once again how 'Cover' in Resistance 2 works.
First, you stop listening to whatever shit band you have on your pink iPod, and turn up the volume on the game. This will allow you to hear the enemy. Enemy guns make 'Bang bang' noises when firing, and no-noise when not firing.
This is clue number one; if you hear 'Bang bang', it isn't safe to come out.
Next, the enemy make all kinds of scary snarling sounds. If you hear scary snarling sounds, it means Mr Chimera is close enough to rip your face off. Apply Shotguns liberally until the problem goes away.
This is QUADRUPLY true of Chameleons!
Next, learn to scout. Pop up and out just long enough to get a feel for the area, and work out how you can attack; use the Fareye where possible on distant targets as its Slow-Time ability will allow you to line up a headshot and duck back again before anyone can shoot you. Use the Carbine / Marksman at all other times. If you have an Auger, you can lock on through cover.
Finally, KILL STEELHEADS FIRST! If you don't, you WILL DIE because Cover doesn't work vs Steelheads.
In short, any player who is in remotely capable should be able to play Resistance 2 without difficulty - you find cover, you jink out to shoot, you jink back before you die, you wait until the Red Ring of Death goes away and then you do it all again. Seriously, it's all about engaging the brain. Yes, a few areas are a little 'trial and error' because you get ambushed, but on Normal that shouldn't be an issue.