I usually start with how densely I want it quilted...if it's an everyday throw for a chair, and will be used a lot, then I would just outline all of the blocks and do a simple motif in the empty white squares...so the quilting will be balanced.
If you want it for more of a show piece, then heavier quilting ...I see you are using the pink check with green flowers for the backing..so maybe an enlarged version of the green flower, and do something like vines and leaves with that flower in a wavy line on the borders?
Anything you do will only add to it's beauty, so try not to stress too much..it will look great when it's done, you can't go wrong when you start with such a pretty top!
Post pics when it's quilted!