Don't use humor – When recording a voicemail message, it is tempting to create an amusing message. However, even if your voicemail is for both personal and professional use, inappropriate humor could cause the caller to form a negative impression of you.
@Fa5t3r - I would try a wide range of different tones when recording and play them back to see what goes over the best and what projects the image you want people to hear. Remember that some people may be going to hear this message over and over again depending on how often they have to call you so you want it to be very pleasant and not at all irritating.

Of course, your phone rang because someone wanted to get in touch. They got your voicemail because you were busy or just not there. If you section off a block of your day to check voicemails, let the caller know so they can expect a time for you to return their call. People will leave more details if they know someone will check it later.
Before you record a professional voicemail greeting, you may want to consider the type of people who might call your home or business. That way, you can think about the information these callers might need before you compose your greeting. Most callers are familiar with how to leave a voice message, so try to avoid giving them instructions. Some things you may want to include in your greeting might be your full name, title, name of your company, and an alternate method of reaching you. If you plan to be unavailable for some time, it can be a good idea to tell your callers when you will return and give them the name and phone number of another individual to call in the event they need immediate assistance. A private voicemail box enables a person to receive telephone messages when the phone cannot be answered.