You need to experiment with Golden’s Clear Tar Gel or Liquitex’s Pouring Medium. These two mediums work the best to for pouring and dripping acrylics.

Just an interesting FYI, since you mention Jackson Pollock, Golden created the paints used in the 2002 movie starring Ed Harris. Ed Harris, while a tremendous actor who throws himself completely into the roles he plays, did not want to work with toxic chemicals for the filming.
Pollock actually used oil based paints, and even house paints, for his paintings. You can research this on the web, and I don’t think I am impuning oils when I say that Pollock’s works are creating some significant challenges for conservators. He painted on untreated canvas… some of the metallic paints he’s using have oxidized.
Anyhow, you should start with FLUID acrylics, not watered down heavy body acrylics… and if you want to increase the rheology (stringiness… if that’s a word) of the paint you can try a medium like Clear Tar Gel, or a pouring medium. Even if you get the paint to be more pourable with water, I don’t think you’ll be happy with how it dries — when the high volume of water evaporates the integrity of the paint film will be compromised.
If you really want intense color, start with straight fluid acrylics and experiment adding mediums until you find the combination that works best.
You should also consider the potential for crazing if you have pools of paint drying, GAC800 is designed to reduce crazing and preserves the surface quality of the pour as it dries. I’d definitely experiment with that as you work through your painting.
Given the relatively high cost of fluid acrylics (quality fluid colors, not student grade paint) you might even start by finding a medium that pours the way you like and then add the colors you want to it. Quality fluid acrylics have a very high pigment load, you’ll be surprised how little it takes to create a very intense color. Plus, it’s really cool to explore the transparency and opacity as you pour and drizzle paint.
Please post up some images as you develop your process.
I hope I’ve helped.

One thing to consider is amount of texture that you’ll want on your finished work. (I’m strictly a novice painter, btw, so I’m sharing what is still a learning process for me!)

I do a lot of my paintings with squeeze bottles, and at first I just diluted the paint with water. Bad idea. The lines would spread out and lose their definition.

A lot of people have mentioned Clear Tar Gel, and I agree. I use the tar gel, paint, and a small amount of water. This way the lines keep some texture, and are much easier to control. One thing that I’m going to start doing immediately is to keep notes….to create formulas that I can return to. I’ve been winging it, and have therefore had a hard time duplicating successful ratios of paint to medium.

Hope that helps. I’ve also bought a LOT of books on acrylics and the various mediums. I’ve found them to be wildly helpful.

If you’re new to painting, use craft paint. Don’t waste money on expensive acrylics, mediums, tar gels, etc.

Especially if you don’t care how long your art survives.

*** Green denotes cynicism ***[/COLOR]