When you dream of smoking and then using an ashtray it means that you want to get rid of your old sentiments and approaches. In other words this dream represents your wish to forget the things that happened in the past and requirement to move on. Alternatively, this dream represents relationships you have been into and now are not anymore, because they were too tough to stay on the track. The other possible meaning of this dream is your wish and attempt to quit smoking.
Read more about dreaming of Ashtray in other dream meanings interpretations.