The vast majority of email spammers send out huge amounts of email with the lowest conversion rates. They rely on the occasional click to make their money.
This is a perfect example of how to learn by example. Study spam emails to learn what does not work well. Make sure none of the emails you send look anything like the spam emails.
Go get a free email account and then post that email to a few message boards. You will soon be receiving tons of spam emails to study.