Each directory has different submission requirements and different editing guidelines. It is important that you familiar yourself with these guidelines before you submit your site. If your submission is well worded then it makes the job of the editor easier and they are more likely to add your site. Also make sure your page is complete, most directories have rules against accepting incomplete sites. This means that there should be no broken links and no sections under construction. If you are not finished with a certain section of your site then you can still submit, just make sure you remove the links to that section from your page.
You need to remember that directories are edited by humans, so your site should be human friendly before you submit. A human friendly site is clean, clear, and easy to use. What's more is that you should refrain from using things that people find annoying. I'm not going to tell you that you should never use popup or popunder advertising, because they do have a time and a place. They not only bring in good revenue but they can also be used very effectively to promote your own site or a service you offer, such as your newsletter or forums. However you might want to consider disabling your popups until your listings are in the directories. Even though the directories have no specific policies against popups, the fact that they annoy many people can definitely hurt you, especially if one of those many people happens to be the editor that is looking over your submission. If you paid for your submission then you really don't need to do this, since you're paying them they don't mind if your site is making money.
Another thing that sometimes people forget about is that you should submit more than your front page. A directory isn't going to spider your site, they won't know what content you have on other pages unless you also submit those pages. This doesn't mean that you should spam the directory with a submission for every page on your site, but it does mean that you should submit appropriate subpages to the appropriate subcategories. Doing this is known as submitting deeplinks. If to reach back to the example of Ray's photography site, he might submit his main page to the photography category, but then he could also submit his film section to the film category, his lenses section to the lenses category, his lighting section to the lighting category, and so on. Getting as many deeplinks as possible in a directory can drastically increase how much traffic that directory will send your way.