Using your unconscious to solve problems is a process of listening and a readiness to record ideas as they percolate into your conscious mind.
Some of the greatest thinkers were great relaxers. Einstein was a daydreamer and spent much of his relaxation time sailing on a lake. Ralph Waldo Emerson enjoyed fishing.
It's all very well to work hard on a problem under the stressful pressure of deadlines, but the opposite condition of relaxation and not working on a problem is very valuable.
A practical application of this technique is to saturate yourself in the problem and then take a break. Write down the problem on a writing pad and leave it by your bedside. The next morning, take that pad and start writing down your ideas. Aim to write three full pages of anything that comes to mind. Explore your dreams.
We all dream, and we all dream a lot more than we think we do. As you get into bed, say out loud: "Tonight I am going to dream about ...." (including a brief description of the problem). When you wake up, lie and bed and think some more about the problem.
The important thing is not to try too hard. Go with the flow. Incubate.