The purpose of life insurance is to cover financial obligations or debts if you die, and your rates are based on the amount of risk the insurance company faces in insuring you. If you participate in risky activity such as mountain climbing, your rates will be higher than someone who rides a bike for exercise. To get the cheapest life insurance, you have to present the least amount of risk, and smoking has been shown to be a risky activity.
How long you have smoked and how much you partake are also factors in determining your rates. If you only smoke a cigarette now and then, but lead an otherwise healthy lifestyle, you qualify for lower rates than someone who smokes a pack a day. If you quit smoking, you will be able to get non-smoker rates, but most companies require you to be nicotine free, including patches, for at least a year and as much as 3 years.
If there are other ways you can lower the premiums, you could balance out the additional cost of being a smoker. For example, bundling your policies with one insurance company would earn discounts. You can also get discounts for building up a good credit score, and keep your insurance costs down by avoiding unnecessary claims.
Keep in mind that smoking increases the risk of a number of diseases, and purchasing a life insurance policy while you are young could mean the difference between being insurable at all in your later years. The earlier you purchase life insurance, the lower the premiums will be over the life of the policy, and you cannot later be canceled because of medical conditions that develop, even as a result of smoking.