Our brief time in the guild finder we did similar--directed people to our website and the application there, and told them not to panic when we declined in game. We also do an IC interview process to help intro our RP. If they can't figure out how to use a simple forum and the post template we provided, well, ok then.

My other RP guild doesn't have a forum app, but they give you a "trial" to complete, some zany IC thing that's tailored to each person and isn't so hard as folks think at first glance.

In both cases, there's an emphasis on patience--I didn't get my interview for a month (thanks, Real Life!) and we tell people we want to see them RP before giving them a trial, an interview--or even before they put in their application. Making people wait a little while, either at a very limited recruitment rank or before they can officially apply, but still come to events and raids, instances, etc to see how they "fit" with the guild can help weed out those who just want perks and a tag they can get anywhere, or someone who really wants to be in the guild for what it is socially.