Learn all you can about the object in question. In order to describe a piece to a museum goer, you have a duty to understand what it is first. If you don't already know the work's provenance, get this information from the person or people responsible for purchasing it. If you don't know a lot about the work's period, do a little bit of research.
Create standard object labels for all of the exhibits in the museum. Whether you use one label or five, if these are standardized, guests will notice the professionalism of your presentation. More importantly, it will be easier for guests to absorb the information if it's in the same place for every piece they see. The Western Australian Museum advises you to consider including main headings and introductory statements, general information (including a basic description of the object), object labels that give the basic context of a work and courtesy labels, in which you acknowledge donors or copyright holders.
Tease your audience with an introductory label in which you highlight the significant parts of an exhibit. Bear in mind that brevity is the soul of wit; museum patrons will likely be enticed by a succinct, powerful and brief description.
Continue with a section label, in which you include the relevance of the object. Kim Kenney, writing for Museum Professionals, advises you to limit yourself to 200 words for this kind of label. That way, your guests will spend their time examining the display, instead of reading your words. Museum goers will be interested to know, for example, if an anchor in your collection was recovered from a shipwreck in the Marshall Islands, but do not need to know the name of the ship's captain.
Highlight each individual object with a label that includes the bare facts. This will be different for each object, but when applicable, you should include the title of the work, the date, the author or authors, where the work was created and the materials used.