When it comes to opinions, we all have one. Just think of sites like Yelp and CitySearch where people post their (unpaid and unsolicited) reviews. If you look at a week's worth of your Facebook statuses, you'd probably see somewhere that you posted an opinion (probably something like "Ezine is the best class ever!" Right? Right??)
But when it comes to writing a 600-word piece, it can seem difficult to find a good idea.
Here's what you need to think about when you're coming up with your idea:
1. Is it newsworthy in some way?
Example: A student yesterday wanted to do a piece on gay marriage but felt it was overdone. But, once he searched Google News for "gay marriage," he found that there had been many developments with regard to how states were addressing the issue. Then, he felt he could write a piece about how Texas was still really far behind the curve. His idea now has the elements of proximity (most of his readers are here in the Lonestar State) and impact -- since most people will, at some point, get married and are therefore inherently interested in the topic.
2. Is it focused?
It's easy to want to take on the world (e.g., "We should all shop local!") but it's hard to come up with specific reasons that back up your point. Here is a good example from last semester of a focused argument.
The Vibe: Why we should use libraries for books rather than bookstores.
3. Can you find plenty of research to back up your opinion?
Sorry, you're not the only expert source you can use. Sure, you can cite personal experience, but you'll need outside sources -- and credible ones at that -- to support your stance.
Some other good examples:
Sports (The goal line piece)
A pro-con piece