I like at least some control to the scrappy -- all reds (but a big variety) as center square etc. Also size of pieces matter if you are mixing jewel tones / brights with more subdued fabrics it is easier if they are small pieces. Don't toss a single big odd color in a section, put small pieces of that color or similar in three places or so.
I'd suggest making good use of a design wall, let the project sit and be viewed at different times. But try somethings outside your comfort zone, if one block stands out in a not good way put it on the back.