The first thing to do is make sure you know the layout before you start the mission. The mission starts at the back of the club by the toilets and you have to escort this guy from there to the back entrance. That means you have to go through the main dance area (or behind it), then past a seating area, through the kitchen and out the back door.
Now you've got to rush to the toilets to prevent anybody killing him before you get there. Here is a tip: if you wait just down the stairs, almost everybody will just run past you or stand there and not shoot at you so you can build up your rage meter and get a better gun, seeing as you're stuck with just a pistol. Now get the VIP to follow you and head up the stairs after you've cleared most of them. Note that no matter how many you kill more will appear, so you have to keep moving. Now once you can see the dance floor, use blind rage to take most of them out and go behind the dance area. Be careful about losing the VIP as he can't keep up with you in rage mode. Now head to the kitchens and then the exit is just at the back there. Pick up the health kit if needed along the way.
Take him to the gate and kill anybody that comes through that door until his car turns up. Loads of guys will come through that door, so blind rage is a lot of help here.
You can now by the club for $1,000,000, which is a lot of money at this stage in the game. Do some drug runs or play as the Enforcer to get some extra money. If you have Montana Holdings it will cost you $900,000.