To mate the chameleons I take the female and hold her outside the male's cage and watch for the reactions. If the female hisses, inflates her body, gapes, turns dark in color, lunges at the male, rocks back and forth, then she is not receptive and you can put her back into her own cage and try again in a few days.
If the female remains calm, walks slowly away from the male, does not inflate her body or darken her colors, she is likely receptive...so if the male reacts to her (head bobbing, approaching her to mount her, etc.) in a way that indicates he realizes she's a receptive female they can be put together.
Signs that the male does not realize she's a receptive female are those he would show to another male in aggression (hissing, gaping, rocking, etc.).
Once they are put together you can leave them together until the female starts to reject the male by hissing, rocking back and forth, darkening her colors, etc. She should be removed as soon as she starts acting this way so there will be no fighting.