It's not that hard.
Start with the item that you want to splatter.
This'll get a little messy, so cover your tabletop if you don't want to get paint all over it.
Get some paint on it, then a generous amount of water.
Mix all that water and paint up on a painting surface so you have a very watery but deep wash.
You can get creative here and dip the water first, then dip your brush into different colours of paint - don't mix the colours on your palette, so they stay separate. With a little practice you can get multicolour or tiedyed patterns.
Flick your brush back and forth over the pole quickly. Only the bristles should touch the pole.
This flicks paint in either direction and you're literally splattering paint on your surface.
Since this is a little messy, you'll run out of your wash quickly so remember to keep adding more paint and water to your brush. If you're not making a splatter, you probably need more water.
For a more controlled effect, only flick the brush one way across the pole. This will allow you to direct the splatter in a single direction. (Gun shot wound, rather than B horror flick)
What looks more natural than actually splattering?