Forum Moderators: phranque
For a lasting long term solution it's best to have a large active site with new pages and updates all the time (which it sounds like you have). The rest is just a lot of hard work and patience using all of the available HTML tags and links. These and another few things depending on the structure of your site.
Try to get a few quotes from some people / companies and ask for specifics on what will they do.
If you see that they will be using any of the following then I suggest that you stay far away from them:
Are they going to make numerous doorway/gateway/entry pages?
Are they going to be using redirects?
Will there be hidden texts on the pages?
Will they submit your site to 1000's of search engines and directories (including FFA & Guestbook pages)?
If you want more information feel free to leave me a message here or using the Sticky Mail option.
Good Luck