The general scheme would be to increase the number of APs, reduce the power at each AP (as necessary per the site survey) and use more zone-specific (sector / patch) antennas.
There's no way to accurately figure out how many APs you'll need without a site survey, and an understanding of what the traffic flows will look like (web or downloads are vastly different requirements).
If you don't have this kind of information (yet), you're driving blind.
Good Luck
Scott