Profiles
Profiles are the main point of information about each other. So it's an important task to fill out "YOUR" profile.
General
Privacy
Pictures
Empty profiles
If a member has an profile, i.e. no pictures, no description, ask him or her to fill in some more info into their profiles. If the person has a problem filling in the profile, you could offer some help if you're geographically close. At couchsurfing you can pre-emptively block couch requests from members with empty profiles ("Edit my profile" page, "Privacy" tab: choose "Yes" for "Contact by complete users only?" Members with empty profiles will then be unable to get "Couchsurf with.." or "Contact" links when they reach your page.)
Additionally, a note on your own profile explaining that only members with completed profiles will be able to contact you, may (one hopes!) encourage people to fill theirs in.