The solution added by LBCeroy is really good, I didn't need it but it's really close to what I did. I wanted to add a couple of tips:
It's easier to do this after at least one playthrough. In other words, the more inventory slots available to you the better.
It's best to do this after buying the keys for the sports car from the Pawn Shop on the second floor of Royal Flush Plaza. This will help you get to your destination fast when you need to get back to the safe house or when you want to go to Yucatan Casino.
Atlantica Casino: On top of the Octopus that's hanging from the ceiling you will find the book ''Juice Boost''. Get this as soon as possible. To climb on the Octopus just go to the spot where you find the Mermaid survivor. Get the book and the juice effects will last longer.
The Quickstep juice is your best friend in this game. I think this is by far the most useful juice, use this and the game becomes a lot easier. When you use Quickstep you walk faster and so does the survivors. They rarely get caught when you use it. Very useful against psychos, when Frank needs health take a Quickstep.
This juice can't be given to Denyce, always have other foods on you.
Fast way to make lots of Quickstep... Go to Yucatan Casino, use the sports car in Royal Flush Plaza the get there going through Slot Ranch Casino and Food Court. Once inside Yucatan Casino head for the restaurant on your left. Behind the counter you will find a blender and an unlimited supply of wine. Mix two bottles of wine to get the Quickstep.
The snipers on the Silver Strip can easily be killed, you don't need to kill them but I find that taking out the guy on top of Royal Flush Plaza and the one on top of Atlantica Casino clears a safe path that can be useful. Some Quickstep and a Laser Sword should do the trick.
For the helicopter fight you don't need to roll under the crane it's dangerous for nothing. Go for the pile of military cases a little bit behind you on your right side near Rebecca. Pick up a box and move it closer. Drop it to a safe distance, the chopper should not be able to hit you where you put it. By the time you do this the chopper will most likely already be on the left side ready to fire just walk to the winch to activate it, if you time this right the chopper won't have time to fire. Pick the military case and throw it on the chopper, repeat this until defeated.
My inventory at all times:
- 2 Coffee Creamer (for Denyce)
- 4 Quickstep
- Books (Juice Boost and Leadership)
- Weapons (Spike Bat, Knife Glove, Laser Sword)