1. Leave a message. A lot of the time I get a missed call and no message; now, I prefer messages by email and my answering service messages all say this, but if you don't leave a message one way or another, you're out of the race at the first fence.
2. Leave a message that tells me who you are, why you're calling - and why I care. Your full name, your email address, your company, your product - and why it is I'll want to speak to you. New product? Event? Interview offer? Feature list request? Job offer? Alien abduction report? How do I know which is which, if you don't say - and if you don't say, I assume it's not interesting. If the message says 'call X from Y on number N', I'm probably never going to call you back. Sorry if that seems harsh; but we're just too busy.
3. Leave your email address. (I know I said this already, but hey). The phone isn't my primary outgoing conduit. It's far more likely that I'll hit reply, search my inbox to reply to you or even type in the email address than that I'll call.
4. That's it!