Once you have your message, you need to actually record it. The exact process varies depending on whether you’re using a cell phone or office phone, but here’s the basic process: Press the voicemail button, or press and hold 1 on most cell phones. Enter your password. Record your message. Listen to the message you just recorded. Follow the prompts to save your message. Following Up on Voicemail Messages
There's no single best way to craft an after hours greeting. The most important point is that you equip your customers with what they need to know, and give them an avenue to contact you, whether that's through voicemail, email, or other channels.

As a real estate professional, you're always on the go. Whether showing homes and apartments to a prospective client or staging a home for sale, it's likely that you're out of the office quite often. Anyone in the industry knows that, out of the office is a good place to be. Unfortunately, it makes staying professional just a little bit harder. What happens when you're working with one client and another one calls? Most likely, you send that call to your voicemail box, but what does your voicemail greeting say? What should voicemail messages include? If you're voicemail isn't offering the right information, you might lose a sale.
Having said all of this, I do admit that I too use voicemail and have been guilty of switching my phone to the out-of-office assistant while I was sitting at my desk because I was in a conversation with someone or was in the middle of a project.