Each surgeon has different rules on this, but the best option is to never resume. Aside from increasing your risk of cancer, and compromising wound healing, it makes you look much older faster. If you are having a breast implant procedure, you will also increase your chances of capsular contracture if you smoke. If you are having anything done to the face, the best thing you can do to maintain results and not show visible aging as quickly, is to not smoke and wear sunscreen. If you intend to resume regardless, I would recommend checking with your surgeon in advance of the procedure to make sure you are compliant with her/his specific instructions.