DD.

Stay away from friends that are trying to offer you a cigarettes, atleast till you gone quiet some time without smoking.

Or make it VERY clear to them that they should not let you smoke under any conditions.
Good friends will try to help you in quitting.

First rule:
No ash-trays and no smoking in your living quarters, the same counts for visitors too.

Second Rule:
If people insist in smoking in front of you, excuse yourself and get some fresh air.

Cheers.