S.K.
When my daughter began this behavior we would give her one warning, then count to three, and if she still wasn't complying we would either physically help her do what we were asking or she'd go into time-out depending on the circumstance. For example, if we asked her to come upstairs to get ready for bed and she refused, we would count to three and then carry her up the stairs. If she wasn't cleaning up we would count and then she'd go into time-out for not listening and as soon as the time-out was over it would be time to clean-up. She is very strong-willed and independent so carrying her when she didn't listen was unacceptable to her so the counting works really well for us. Now she is in preschool and they use "1-2-3 Magic" (I forget the author) so the counting is reinforced there and we don't have too many of the behaviors anymore, or when we do the counting works really well for us. Good luck!