Funny how the costume I spent the least amount of time on end up being the costume that gets praised the most XD;; I didn't really want to cosplay Misa originally, but I wanted Silver_Ruby (here on cosplay.com) to cosplay L and she then dragged me into cosplaying Misa.
I bought the Wig off cosworx, it's the 613 bleach blonde Pat wig, found under medium wigs with bangs. I didn't like how the ends of the wig kind of flipped in though, so I straightened it using a hair straightener first on the lowest heat setting (although technically you're not supposed to do this, many people advised against it) and then using the hot-water technique to straighten it more. It didn't really work all that well but it did flip in less, so I was satisfied with it.
I used my old school uniform blouse and bought 3 yards of a thick lace trim at Walmart, and added the trim to the collar and bottom of the shirt and also to the sleeves collars.
As you can see from this (http://olivtom.free.fr/deathnote-fr/images/raito_misa.jpg) reference picture, the ends of her sleeves are not flat but kind of in a reverse teardrop shape, so when I sewed the trim on I kept that in mind and sewed it on to create that shape, then cut off the excess parts of the original sleeve collar that was showing.
From that picture the bow is actually a red tie that is tied into a bow; that's why one side of the bow is smaller than the other side, and why the ends of the bow are pointed and different sizes. I had a maroon silk tie that I bought specifically for this cosplay, but I forgot to bring it to the convention so I used red satin fabric to make a normal bow instead (making a tie is harder and I was pressed for time at that point).
I couldn't make my hair look like the style she had in that schoolgirl picture, so I put it up in her usual style (http://www.age.to/~dizzy115/death/deathnote_image/kenka.jpg) instead. I also forgot that her socks are black and white, not black and red, (but I changed into the correct black and white one later XD;) and I'm also missing the cross earrings and necklace, both of which I had, but stupidly forgot at home T__T
Instead of making her black skirt, which looks multi-layered and flappy and unecessarily complicated, I used a skirt I bought in Harajuku, Japan. It's similar and it's also black, but also with a lot of more gothic decorations such as metal studs, chains, skull and crossbones and red and white letters in gothic print on it.
Despite the (what I hope is) minor descrepancies with the costume, I seemed to be very recognizable and people liked my Misa costume, and I had an awesome Raito and the smexiest L to take pictures with to boot, so I am pretty satisfied with my costume. I definitely will keep improving it until I can deem it fully 100% complete, though!
EDIT: I scrapped the wig after several helpful critiques pointing out that the wig is too short. The wig is actually the same length as Misa's in the manga, but because it flips in and sits rather high on my head, it appears a lot shorter. I plan on getting a new wig for this, one that's longer and a slightly darker shade of blonde.
NEED: 1) new wig 2) shorten bottom of shirt 3) remake tie 4) the cross necklace 5) re-sew on lace trim 6) new DeathNote