1.  If it doesn't take place at 4 in the morning, immediately change the setting.
2. You should center all your work. Centering makes the piece unique and improves readability.
3. You should invoke the idea of The Mask. Paul Laurence Dunbar didn't do it well enough.
4. One word lines improve readability and do a great job of making emphasis. Use them a lot.
5. On the other hand, really long lines explain points wonderfully. Feel free to be essentially prosaic.
6. The subject should be obvious and everyday, that way everyone can easily understand what you're trying to say. Subtext is dated.
7. Confessions and heartbreak are unique to you.
8. Not editing makes the work extremely human and relatable.
9. Emoticons and the ilk are the cutting edge of the English language. Feel free to use them without reservation.
10. Rhyme scheme doesn't need meter.
11. Making a word into waterfall letters tells the reader you're falling apart (See #3).
12. Journals, diaries, blogs and Tumblr are old news when it comes to venting. Write an angry poem about your day instead.
13. You're probably going mad according to the DSM-5. Definitely write about that.