I'd suggest going back to the hairdresser who did your Deva cut, and asking for advice. One of the big selling points for Deva cuts is that consumer education is supposed to be an integral part of the process. My hairdresser has been great about teaching me as she goes along, and giving me help in between cuts, and always tells me to come back if I have any problems.

HTH
Peace,
Morgan

Baby Fine 3B, low porosity, normal density and elasticity
CGing since July 2008