Give up zina, watching porn and smoking

Smoking is not a sin. However, it is undesirable. As far as the other two actions you mentioned then these are major sins. You should sincerely repent to Allah Ta'ala for committing them and make a firm resolve that you will never return to these evil deeds in the future. Think about the evil consequence one will face in the grave as well as in the hereafter on account of committing such detestable deeds. It appears in the Hadith that in the manner a person leads his life that is how he will pass away and leave this world, and the manner he passes away he will be resurrected on the day of Qiyaamah. Imagine being resurrected on the day of Qiyaamah with those dirty and filthy people one enjoyed viewing or one committed the evil sin of zina with! Make sincere tawbah and attend the programmes and gatherings of the pious. If you are not married, then you should get married. May Allah Ta'ala assist you in reforming your life.

And Allah Ta'ala (الله تعالى) knows best.