Let me first say that I am in no way a seamstress, and am not very skilled at sewing. But I know my way around a machine and do well enough to put together costumes for myself.
I sewed this Harley Quinn costume completely from scratch using this Kwik Sew pattern – A. I just modified it so the zipper was in the back and I cut the left and right halves of the pattern just like the directions said to, one red and one black. Then cut those in half just above the waist and sewed them together, following the rest of the patterns directions.
The collar and hood I just put together myself kind of trial and error. The final collar was the second I made and the hood took lots of adjusting to get it to fit right, but I just kind of winged it. Both pieces should have had little white poofy balls attached as well, but time got the better of me and I just didn’t get a chance to add them in.
I found some grayish boots at the thrift store and spray painted one red and one black.