Danny, I’m just trying to help. C’mon, we used to talk all the time.
Headband: Typically it’s difficult to tell if a character from a cartoon is wearing a plastic or elastic/stretchy headband. This isn’t the case with Jazz, as she uses her headband to tie a note to an object in the episode The Ultimate Enemy. Your headband should be a teal to aquamarine color such as this one which fits up to adults.
Shirt: Jazz is wearing a black long sleeve shirt with a v-neck. Typically these are super easy to find but just in case you are having trouble, this one should do nicely.
Pants: I’m not sure if you really need to go aquamarine or teal as much with the pants. In fact, I think you can get away with being a bit more natural looking. A pair of jeans that are close though will help cement the cosplay more. A pair such as these (left top picture) or these (right top picture) to me look more natural than a pair like these (bottom picture) anyhow.
Shoes: Black ballerina flats seem to be a staple for cartoon characters, and Jazz is no exception (Mabel from Gravity Falls owns a pair). I actually own a pair of these ones in yellow that I purchased for my Joy cosplay, and they are very nice shoes.
Which character do you want to see featured next? Leave a comment below with a suggestion and I will see what magic I can work for you!