First one, shut up for a half hour or so just to give the your voice a rest!!
Two, I actually use a hot toddy - a nip of whisky, lemon and honey - it provides a sort of anaesthetic plus the alcohol helps loosen the voice up a bit. Once I've had that one nip I tend to be able to reach pitches lower and higher than if I haven't. I hate to play the devil's advocate but.....
Tell me though, are you just reading for auditions, or are you singing as well? Either way you DO need to cut the ciggys, because they're putting a dreadful strain on your voice and your lungs - cruicial for the volume you need for theatre - plus who wants to hear a crackly old smokers cough on stage?
There are various exercises you can do - for exaple sing arpegios starting from your lowest pitch and then working upwards in halfs until you can't reach any higher. try that