Check to make sure your URL isn't already listed. Believe it or not, there are many human-edited directories out there where people who do the editing will seek sites out.
Read the submission guidelines. If you submit a website we find inappropriate for this directory will be immediately deleted. No two directories will have exactly the same rules.
Search through the directory to find the absolute BEST place to list your site. Don't try to list higher up in the directory thinking the PR would be better or that it will be seen by more people. You only get one listing per directory usually, so make it the most relevant category available.
Don't create a title with more the 50 charachters. Also the description should begin with your company's name and end with a dot.
Check out the titles and descriptions that are currently listed in the directory. They're likely NOT full of hype words like "best" or "#1.