Take advantage of the weapons at your disposal to make easy kills. Try and use shotguns to take out enemies as much as you can and use pistols for long-range head shots. C4 explosives are useful for blowing up doors to kill or surprise the enemy.
When you play the Fremont Street level look for a ledge on one of the buildings that has a bottle of Axe cologne. When you shoot the bottle the neon roof of the Fremont Street Experience will change to an animation of a girl in a bikini promoting Axe items. This sequence is then followed by a sequence with outtakes and early animations.