First off, you need to have a ski with a sintered base, not an extruded base. Extruded bases do not absorb wax well, but they are ok for those looking for a low maintenance or cheaper set up.
After you hot scrape your bases, going through the waxing process (waxing, scraping, brushing) over and over again is one of the best ways. If you are serious about having super fast skis, you can have them hot boxed. Hot boxing heats up the entire base evenly and lets the wax deeply penetrate the base. It's usually expensive and it works really really well, but it's not something I would think anyone here would use.
Just properly waxing, scraping, brushing over and over again will work really really well.