Advertise "Shared Tree" under FamilySearch logo
Adding a "Shared Tree" byline under the FamilySearch logo would go a long way to reminding newbies that the tree is not their private area for 'testing' relationship theories where records are slim to none. Over the past few years I have encountered several new users who are used to working on private trees in Ancestry who come in and bulldoze years of research and work done by other. In most cases, with a polite Message, I help them realize that it's a shared tree. Most are embarrassed and apologetic for creating work to reconstruct the tree with hard-to-find proofs etc. Some parts aren't too hard to piece back together using Latest Changes but other things can be much more difficult to reconstruct.
What also might help is a FAQ or orientation help page designed specifically for Ancestry users.
Also, perhaps rather than "shared" a better tag line would be "collaborative". To me, shared does not mean collaboration. Collaboration includes sharing.1