Quite simply, don't blend and don't tidy up. Allow the marks left by the shape of the brush and its hairs to show. Don't brush back and forth to eliminate lines left by individual hairs from the brush. Be decisive and bold in moving the brush across the canvas or paper.
Follow the direction, contours, and main shapes of an object. If you're unsure, think about how you would hold the object, how your fingers would curl around it or how you might run your hand across its surface. That's the direction you want your most dominant brushmarks to head in.
Don't neglect the background. At the very least use two different tones to create some visually interesting pattern or shifts in color. Or, for instance, if you've a dancer spinning around, paint the air they've disturbed.
Is it really that simple? Well, yes and no. It's easy to do badly so it's a wild mess of brushmarks that a viewer can't interpret. And it can be hard to resist the temptation to "just quickly touch up this bit" and so overwork an area. As soon as you find yourself fiddling or hesitating, stop and leave the painting overnight for fresh consideration in the morning. Practice and persistence will see you rewarded.
If you have the opportunity, supplement your painting by looking at actual paintings done in this style. Stand as close as possible (with your hands clasped behind you so the gallery guard doesn't start to panic you're going to touch the painting) and spend time studying the paint and brushmarks, not the subject of the painting.
