Hopefully you guys can follow this. This is the easiest way I've found to return any straight ponytail wig to its frizz free glory.
Any Miku or Linalee cosplayer knows how bad these wigs can get the moment you put it on, let alone halfway into a con. With the above methods though my wigs look brand new every-time I use them.
Added benefits is the product left in the wigs from this process makes them slightly less likely to frizz.
EDIT: The little pink bottle of wig spray is from [link]
Ive found it makes wigs AMAZING to brush through and doesn't smell or get all over the place, plus better for travel!
If you need some and you dont have time to order any, mix up some fabric softener and water in a bottle and spray that on!