Via ThoughtCo, I came across this article on Techniques for Painting More Loosely written by Marion Boddy-Evans. Here's a few ideas you may want to try:
- "DON'T PAINT OUTLINES. Objects are three-dimensional, they don't have outlines. If you're unsure about this, look at your body and see if you've got an outline or if you're 3-D…. Instead of drawing an outline (or painting one) and then filling it in, paint the object as a whole."
- "TRY UNREALISTIC COLORS. Instead of worrying whether you've painting accurate colors, try some that are completely unrealistic. Paint a self-portrait in your favorite colors rather than skin tones. The result will probably be a lot more emotive – and certainly dramatic."
- "USE A BIG BRUSH. Painting with a big brush makes it hard to put down detail. A big brush encourages you to use your whole arm to make broad, sweeping strokes. Use a flat brush not a round one because you're wanting to increase significantly the width of the painting strokes you make."
Check out the complete post for more ideas from Marion.