Make sure you list your site in the proper category. Note the categories of the page your on so you can submit your site in them as well. This means that you DO NOT list your web site in the regional category if is not a regional site. Just write a good description of 15 words - 25 max. If you go over 15 words they may end up editing it.
Self promotion is a no-no.
Make sure the keywords you use are the honestly describe your site. If you have a keyword in your title or your actual domain name, this is can increase the keyword listing of your site. You may NOT have heard. Submit your site once, if it's not listed in three weeks, submit again, if it's still not listed do not submit again. Taking this route will help you avoid being banned because of spamming.