Mix paint so it won’t flow, or so it will drip unexpectedly and in the wrong place, or will dry a different colour, or so it cludges or pools.
Choose a brush that doesn’t work, has its bristles all askew, is dried up like a stick, or is a stick, or a grass stalk, or the hair of a dog, or a clump of your own hair bound with string, or paint with the string.
Choose a canvas that has holes in it, is the skin of your lover, or the hide of your ex-lover.
Take a large garbage bag and into it discard: your concerns, your politics, the shopping list, your body, your hard-earned craft, your ego, your desires, your name.
Look at your subject (if you have one.) Stare at it a long time. Stare at it until it shimmers like illusion. Stare until it dissolves behind its own negative.
Now, paint what it isn’t. Don’t look at what you’re doing even if you can see, just keep sticking your branch in the paint and the paint on the canvas.
Some time after you’ve finished you should look at it. Is it clever? Are you in it? Who did it? If you can answer these questions, throw it away.