If your a Raze fan, and you need help, ask me as a comment or here. I've got LOTS of tips. Seriously. I know about good snipe spots, campaign help, what weapons you should use, strategies, and much more. Just ask my friends. (Shouldn't the creator of Raze do this? Yeah, I know. Don't comment about that.)
The alien campaign is harder than the Human one so you have let the team make the job and try to stay alive the most you can. Try to find a spot where you can shot at the others. In this level, pick up all the shields and double points you can and don't let the Juggernaut go to far from you.
I disagree with a few points of the weapon ranking. The chaingun is actually OK, if a little weak. I would rate the worst weapon as the bio uzi, because of its short range, relatively low power, low accuracy, and less than brilliant rate of fire. The assault rifle is actually ok - better in many ways than the pistol; and the zapper isn't that good - it has extremely short range, even if it is high powered.
the weapons you like will depend on your fighting style, and your experience with them. the more you use it, the better you get, the more you like the weapon. for example, i never used the zapper before. now it is one of my favorites and i have adapted my fighting style to cope with its short range.