I highly recommend that you check out this page. One thing he mentions on the above page, and something that I totally agree with, is that certain search engines are so important that they deserve your special attention. This means that you should personally visit these sites and add your web page manually. One important search engine, Snap , does not accept automated submissions. Remember that some search engines like Yahoo are several months behind.
Submissions is just a suggestion.
It does not guarantee that they will list you. The longer your site is online, the more, and the better, it will be listed. When I do a search, I often find pages on my site that I had completely forgotten about and that have been online for 3 or 4 years, even though I have newer pages that are more appropriate for the search. These newer pages often don't show up at all. Below I have listed the major search engines that you should personally visit and manually submit your web page to.