sashing/borders on some sides of some blocks , graphing out on paper and then adding blocks/fabric where needed - I've done it a few times and also have thrown the blocks up on my design wall and played until i got a pleasing set and then added where needed and sewed together as I went -- yes, there were some Y/partial seams at times, but those aren't too hard once you get the hang of them
here's one I did:
https://www.pinterest.com/pin/118782508898933102/ with toile in different sizes
and another I did:
https://www.pinterest.com/pin/118782508895830398/ with preprinted sayings and other misc sized blocks
Do try to have some larger blocks made up of smaller ones, so that you have some straight lines. If you parsed those two quilts you could see the larger irregularly sized blocks....