Following pattern on first 4 rows hat was too pointy at the back. Adapting pattern:
Foundation: ch4, dc 11 in first CH, ss on top of ch4
Continue working in multiples of 12 instead of 10
Made 9 rows of dc following pattern but with repeats of 12 instead of 10.
3 rows of sc, increasing to 90 sts.
Followed pattern for lace part of hat working with 1 thread only.
Finished with 1 row of sc all around, skipping sc st between dc clusters and 1 sc in each ch2 space in 4dc clusters.
Added 3 colourful flower buttons to hold brim.

Might sugar starch the brim to hold it around:
http://www.crochetspot.com/how-to-stiffen-or-starch-croch...