I usually look to the fabrics in the quilt for a design. If possible, I try and find something that I have already drawn or something that I already have a stencil for in house. Sometimes, I just have to get out a pencil and paper and start drawing so I can get the scale just right. For a project I did this week I chose some wonky stars.
Before I load the quilt, using white school chalk, I mark the areas I want to quilt the chosen motif. This way I can balance the designs throughout the quilt. For this quilt I put the stars in various groupings using some stencils. (I find miracle chalk in white works the best.)
I used white thread to quilt the stars. I then changed to a bright variegated thread and did swirling meanders around them.
I also did some single stars in places where they would really show. This quilt had a lot of colorful fabrics so it was difficult to get some contrast.
However, the white stars really showed up bright on the red backing.
When I don't use stencils, I will get out my laser and quilt from paper patterns. If you sew on a domestic, cut the shape out of freezer paper and iron directly onto the quilt. Then simply quilt around the paper. I have used this method to quilt in turtles, bears, stars, boats, to name just a few. Hope this gives you some ideas on what to quilt on your next project.