This one's really tricky, because one thing you have to determine early on is whether or not the person really cares to understand at all.
Metaphors can be terribly dangerous because of personal experiences. For example, I've seen people explain object-oriented programming using biology or automobiles. Those sound great until you think about how many people don't relate to those metaphors.
Other people don't care. I don't care how my cellphone works - I care that it works, and if you tried to tell me how it works, I'd tune you out. It's not in my scope of give-a-damn, you know?
If you feel you're terrible at explaining things to non-technical people, reflect on whether or not those people really need to know those things.
If you determine that they are interested, and that you are unable to adequately explain, consider finding situations where you can understand their side of things. A great way to do that might be to learn how to do something that they do. When I meet a new client, I ask them to explain very technical parts of their job to me. Then I am the person on the receiving end of that. I can observe how they explain things, and I can empathize with them when my eyes glaze over. :)
Hope that helps a little, or at least gave you some ideas.
Sometimes it's as simple as politely asking. "Hey, are you interested in knowing how this works?"
IT people tend to assume that everyone is just as interested in stuff as they are. It's not a great assumption to make. Just cos you think it's cool doesn't mean everyone does. And that's ok.
I've been teaching some folks how to code. It's helped a bit. I also have been reading more business books - things like the personal MBA [1], The Goal, how to win friends and influence people (old versions before he died). Basically, make an effort to speak their language, because they (probably) won't put in the effort to learn yours. Some will appreciate the effort and meet you half-way, others will be amazed that you can communicate with them.
First, you need to have deep technical knowledge. If you have trouble explaining something to non-technical person one of most common reasons is that you don't fully understand it yourself.
Once you are sure that you have thorough understanding of the topic other ways to improve include reading books, especially science fiction and popular science to expand your vocabulary, and writing a technical blog.
Metaphors can be terribly dangerous because of personal experiences. For example, I've seen people explain object-oriented programming using biology or automobiles. Those sound great until you think about how many people don't relate to those metaphors.
Other people don't care. I don't care how my cellphone works - I care that it works, and if you tried to tell me how it works, I'd tune you out. It's not in my scope of give-a-damn, you know?
If you feel you're terrible at explaining things to non-technical people, reflect on whether or not those people really need to know those things.
If you determine that they are interested, and that you are unable to adequately explain, consider finding situations where you can understand their side of things. A great way to do that might be to learn how to do something that they do. When I meet a new client, I ask them to explain very technical parts of their job to me. Then I am the person on the receiving end of that. I can observe how they explain things, and I can empathize with them when my eyes glaze over. :)
Hope that helps a little, or at least gave you some ideas.