When your small business is closed, ensure that your callers know that! If appropriate, you might want to reiterate your business hours to manage callback expectations.
Users often don’t invest enough time into their messages, resulting in incomplete, unprofessional, or otherwise under-whelming greetings. Sure, crafting a greeting doesn’t sound all that complicated; however, there are a number of pitfalls users can fall into—i.e. informality, terseness, sincerity, lack of direction, and more. While none of these sound too catastrophic, they are often interrelated. As such, they tend to worsen any problem. For example, humor can cause informality, worsen ambiguity, and weaken sincerity. That being said, users should strive to avoid ALL these pitfalls.

Don' let background noise do the talking for you. Ambient noise on your recording could be sending the wrong message to your clients. The sound of your kids arguing in the distance could be the sign of a distracting work environment. Clinking glasses and restaurant chatter may leave the impression that you don't take your work seriously. When you record your voicemail greeting choose a quiet spot free from interruption, so your message is the only thing callers hear. It's also good to avoid large, cavernous spaces where sound verberates.
You want this experience to be a positive one for the caller. Make sure your voicemail provides information such as your hours for operation and additional contact information. You’ll also want to address when the caller can expect your call or list other ways they can get in touch should you not answer.