Assuming you mean how to be a healthy weed smoker, there are a few things you can do.
First, don't smoke too much. If you're smoking every day, try cutting back to a couple times a week. Second, invest in a good bong or vaporizer. This will help minimize the amount of tar and other carcinogens you're inhaling. Third, make sure you're eating right and staying hydrated - marijuana can dehydrate you so it's important to drink plenty of water and eat healthy foods.
Fourth, take some time off every now and then. Just like with anything else, your body needs a break from weed occasionally. So give yourself a few days or even weeks off every now and then to let your body recover. Lastly, pay attention to your lung health. Weed smokers are more susceptible to bronchitis and other lung problems so it's important to take care of your lungs by not smoking too much and by avoiding tobacco products altogether.