This is an ever-evolving page.
Create a cover page
Many pieces sold online do not include cover pages, which means that if you include one, your piece will stand out! The buyer does not need to print the cover page, so it won't cause a "waste of ink".
Include some text
Directors often include some text in the program or speak between pieces. It saves them a lot of time if you provide the text for them! You can include some historical background about the original composer, some cute story about how the piece came about, or some technical information about what techniques are used in the piece and why.
Use a "catalog number" system
If you only have a few works available, not having a numbering system is not a big deal. However, as you grow your product offering, you may want to consider creating such a system so it will be easier for buyers to find specific pieces. Example: you may create three different arrangements of the same piece with the same title but different octaves and difficulties. The buyer won't be able to distinguish between them unless they look at the description, or the easier solution: a number!
Pick an engraving software and stick with it. MuseScore is free and is continuously being updated. See below for MuseScore help and general info and tips for handbell sheet music.