Listen to the great punk artists to learn from them: The Sex Pistols, the Ramones, Nina Hagen and Siouxsie & the Banshees. Take the time to download their music and get a real education about how punk is done.
Tap into your anger, rebellion and angst. Punk music is about channeling all these emotions and creating a sound that is daring and original. One has to be brave to write punk songs because self-exposure is rather mandatory. So, give your emotions free reign.
Feel the adrenaline rush of total expression. Set your pen or your keyboard free and write songs that make people want to get up and move. Total expression of the self and of all the pain and uncertainty of life is punk.
Watch some movies that evoke the punk attitude. Check out, for example, "Sid and Nancy," a film that looks unblinkingly at the painful and sometimes ingenious life of Sid Vicious of the Sex Pistols. This film, and others like it, are sure to help you better understand the punk vibe.
Create a world on paper where everything is accepted. Punk music is about liberation from the status-quo attitude that traps most of us in our small lives. Punk takes us beyond that realm into true freedom.