I have made two Warm Wishes quilts, plus a third which I abandoned after I had all the squares sewn. And I also have trouble picking fabric...however, I believe what you have could work really well. The four fabrics work well together, or I think they do.
My advice would be to play with your fabric a bit. I just decided my next Warm Wishes by cutting out six of the six inch squares out of my focal fabric, and then sewing one strip of the three colored squares. Then I cut that strip up into the six inch pieces and laid them out to see if I liked where it was going. I decided to change one of my fabrics after I did that.
The ONLY way I can decide fabrics anymore is if I try to create one block or, in this case, one section, so I can actually see it as it might end up looking. :)
Hope this is helpful? My pattern says to put the lightest fabric in the center of the three fabric block, but I don't know if that is really a rule. It is what I have done so far, with pretty good results.