- don't smoke it until you are at least 25 years old. Human brain develop until that age and you don't want your childish stupidity to determinate your future life. Kids under age of 16 are especially vulnerable.

- newbies smoke it in small quantities. Modern cannabis is a very potent drug and can be compared (or even more dangerous) to many hard drugs.

- don't get addicted to it. Don't smoke it daily and don't make a habit of smoking it. Do it recreationaly. 

- weed can cause psychological problems. It can induce anxiety, depression, panic attack, psychosis or schizophrenia. It can cause insomnia which can become permanent for some. Keep in mind that mental health is very important.

- if your pot use has induced any of those problems keep in mind that they will probably go away with time. But it can take years.

- some people experience bad effect first time they smoke it, some after years and some after decades of chronic use. People who smoke it daily for decades will probably have all sorts of mental problems.

- there are not many people who can smoke it chronically without having any negative effect on their lives. Even people who seem successful and smoke pot have many problems, they just don't talk about them (or they use pills to hide them)

- people withdraw differently from cannabis. Some can be fine in a few weeks while some need months to fully recover.

And last one: BE SMART!