Do's and don'ts of forum posting contests

Do's and don'ts of forum posting contests

Creating a posting contest is an effective way to stimulate forum posting. The key is to make the contest last a long time, such as one full month, rather than simply a week. There could be a downside to having such a long contest in that members could get busy and forget to post or get bored/discouraged with their posting and simply quit posting. Other things to consider for a 'post the most' contest would be spam prevention as some new members will simply post one liners or quick answers to hike post count. You'll need lots of spam moderators to delete these posts. What are some other things you should be considering when creating a forum posting contest for your site?