While this may be specifically for cosplay, this technique works really well!
Just know up front: wig ventilation (aka: adding more hand-tied knots to a wig) takes FOREVER. It seriously requires a lot of patience and good eye sight. (There's a reason why fully hand-tied wigs are so pricey!)
This tutorial was written by Firewold826 and her page can be found HERE.
Thank you for the fabulous how-to graphic!