I started including the depreciation schedules when I got new clients that didn't have them, and discovered what a pain that could be. One client I got had his preparer die suddenly during the year, and had a heck of a time even getting his docs back, much less any prior year info, like depreciation schedules. I'm currently trying to deal with a habitual late filer whose prior preparer is insisting everything is in the tax returns..but there is no depreciation schedule, and his main source of income is a 2 unit rental. I've scoured the returns I have, but there have been too many things put into service, including improvements, plus him converting one unit from personal to a rental that I simply cannot recreate the depreciation from what is contained in the 4562s I have.
I put the tax return with the necessary reports (but not worksheets) in an ATX-styled return cover, and their docs in a two pocket envelope, unless they only have a few in which case I staple them in back of the return. I make copies of all of the docs I used to prepare the return, although I'm slowly switching to scanning. I'm starting to include two year comparisons, adding them somewhat haphazardly to the returns each year. I have personalized pens and refrigerator magnets I give out. The magnets are new this year, and my first efile client today specifically asked for one. She loves the pens, and I usually have one or two on me. For awhile I had run out of biz cards and just gave out pens. I've also had compliments on my tax package. It looks very professional, and the return covers don't cost much.