1. Move the Conversation Forward
2. Be Brief (try for under 1 minute)
3. Leave Your Number
4. Speak Clearly
The rest of this post is backstory to those rules. I've started listening to another Podcast on iTunes, Manager Tools. The hosts (Mark and Rich) talk a little too much, drowning key points in between banter. They acknowledged the fact that they talk a lot, and it is just their presentation style for the podcast. To their credit, there is a level of authenticity in the conversational aspect of the podcast. They do have very good points in the podcasts, worth listening to. There are few other places where one can find the information they share.
That being said, the basic concept of "moving the conversation forward" is lost on a lot of people (myself before they noted it in the podcast). Voicemail is a way of continuing a dialogue with a person, even when they are not available. To say "Hey, it's [name], call me back" doesn't move the dialogue forward. Respect who you're calling, leave a message that actually says something. I've found it helps to know what I'm going to say on a voicemail before I call someone. It is good planning in case you have to leave a voicemail, and helps the other times when you get through, leading to smooth conversation.
Other episodes of this podcast I recommend:
image courtesy gene