If you want to improve your voicemail performance, get deliberate in your practice. This means creating a highly structured practice routine that offers ample opportunity for repetition and immediate feedback.
Remember, you are not trying to cram your entire conversation into the voicemail, but rather, get the person to call you back to have that conversation. Your voicemail should answer the following questions: Who are you? / Where are you from? Why are you calling? How can they get in touch with you?

9. Update Your Greeting Frequently. Many of the things that can make your voicemail great, also require that you update it pretty regularly. Information like deals you’re running, when you’re away, and who to contact while you’re out can take your greeting to the next level, but they’re obviously time sensitive.
Increase the odds of getting a call back by mentally composing your message before each call. And remember, people hate it when callers state their name and phone number too quickly in voice mail messages – no one wants to listen to a message ten times to comprehend simple information. Begin by saying your name and company (if applicable). Then assume the person you’re calling doesn't have your number, so say your phone number twice. If your name is at all unusual, spell it the first time you say your phone number. Talk slowly like you were writing it down yourself. The second time you say your phone number, you can say it at your normal rate of speech. A gracious phone message is no longer than 30 – 45 seconds. Be pleasant, but also get right to the point. Keep your voice mail message to two points maximum. If you need to share more information, then say you will send an e-mail message with the rest of the details. Leave a specific message. There’s nothing more frustrating than a voice mail that says, “Hi, it’s me. Call when you can!” Even if you’re just calling to say “Hi”, tell them that in your message. End on a high note! You don’t necessarily need to say “Goodbye” at the end of a voice mail, because you didn’t really talk to anyone. Instead, try something like, “Look forward to talking* with you!”