Try to use a hinge that removes easily and that won't rip the stamp. If you want to sell a lot of low value stamps, mount them in sets or batches in glassines and use the book pages to your advantage. If you want to write in comments or details on the book pages, go ahead - it's your sales tool. You don't have to completely fill the book if you run out of material. Members who mount circuit books often ask what I need.
Covers can be hot - as in the case of the Finnish covers that sold in a day.
Specialty items are popular. Many of our members are specialists, so sales of good, rare, and expensive specialty material is not a problem. For security, I photocopy all pages of a book before sending it out on the circuit. I do randomly check incoming books against these copies, but have never had a problem. I don't know of any other hobby where honest and trust between members is so easy to come by.