One of the things I use when free piecing is the question frequently asked by Jude Hill over at Spirit Cloth...."What if?" (She used to have a collaborative site dedicated exclusively to that question, but it appears it is no longer up.) Asking this helps me be open to possibilities and exploration, rather than set plans and outcomes. Each step becomes a process of discovery...what works and what doesn't, how one piece changes the whole, how I can fit different sections together, etc. etc. Perhaps thinking of your block as an experiment (without worrying about creating a masterpiece!) will help get the ball rolling. Here's what I experimented with on my block and the end result.
Like you, I began with two groups of fabric, light and dark, in assorted shapes and sizes. No set has all the fabric. Mine had lots of blue and said "sky" to me.
I started with the "dark" or "shadowed" side. First, what if I start with stripes?
Then cut it in half? What if I want stars like these? Just lay that big piece of yellow across one corner and stitch it down. Flip it over, trim and press. Trim again.
Another point amidst the stripes.
Do I want three or four points? Lay them out and see.
What if I just can't make four work? No more of that yellow and these improvised pieces are just cut all wrong to come together in any logical way!
This is how they work...but what if I don't love it like this?
Oh well...move on! It will do.
What about the little scrappies of yellow that are left? Could they go in the lower corner? Get out the rotary cutter and cut that corner away for the new piece to fit in.
And now the "light" side!!! What if I start with stripes again?
And if I don't know exactly where to place a piece, I just put right sides together, sew and trim. (I also keep my seam ripper nearby and use it as needed!)
Piece things together....
Finished! Leaving it raw and wonky (not squared up) gives me more options in piecing it together with all of your blocks.
Along they way, I created a fair little mess of the bits I trimmed away and didn't use. Most of them will go in the trash. The larger ones will be saved to fill in between the blocks. I didn't really use any of the red...they just didn't fit with my image of sky.
Do I love, love, love my block? Nope. I love elements of it and I hope it will contribute something to the whole. That's part of what I am interested in...the process of pulling all these different experiments together into one cohesive whole. So truly...experiment. See what you love. See what happens along the way. Don't worry if things don't turn out how you imagined them. They'll turn out just as they should and find a way into the whole of this quilt.