It's not really directly related to getting visitors, but instead, submitting to directories is useful for getting backlinks to your website. This will help with your ranking in search engines, and in turn, I guess you do get visitors if your site is well-optimized. It usually takes more than submissions to directories to get nice ranking on search engines, though.
if you don't have the time or find it boring, paying someone 50-60 dollar for submission to 300 directorys isn't bad at all. Try getting visitors from forums at the beginning when you are new to search engines, because be sure that directorys won't bring you traffic. optimize your site and stick to your keywords and you will be fine