I've always enjoyed the look of marbling; here's a pretty simple way to create your own marbling with paint at home! You can use whatever paint you'd like as long as it's fairly liquid in consistency--it needs to be fluid enough to move around the canvas.
1. Set up your workspace and canvas. To help keep your workspace clean, you can set up a plastic table cloth or trash bag.
2. Select your paints (make sure the paint isn't too thick so it can spread). You can also think about color schemes; I like to work with monochromatic and analogous (colors next to each other on the color wheel) color schemes.
3. Add your paint. (I don't stress over color placement too much; just make sure the paint is somewhat evenly spread out over the canvas surface.)
4. Get a plastic bag and press the bag onto the paint-covered canvas. You don't want to spread the paint too much, but it helps to spread the paint out so there aren't any huge blank areas.
5. Carefully remove the bag from the canvas.
6. Optional: You can use the excess paint on the plastic bag to make a print on another surface/canvas if you'd like--my prints have turned out pretty neat.
7. Tap the canvas edges down to help spread and mix the paint to create a marbling effect. You can tap until your satisfied with the paint's movement. It's really up to you when the piece is "finished" (although if you keep tapping for a long time the paint might become extra mixed--that could look neat; I haven't gotten to such a point yet, though).
8. Then you're finished! Allow the paint to dry before moving it to hang in your house (unless you want paint to drip on your floors/surroundings--I guess that in the realm of possibility, so you do you ^_^ ).