Explain that its like a videogame but you're the computer.
Use a mat and minis so people can see what's going on. I have a lot of mini's for this, make them visibly different.
Use differently colored dice, so instead of saying a d8 you can say "the red one"
Ask people what they want to play and help them build their characters: its a nice mix between not liking the game because you get stuck with a class thats not you and not liking the game because you made a character with a severe flaw that can't do anything.
BigNorseWolf has a very good point. I've run a number of games in the past few years, and I always seem to be attracting new players, or players who have never played DnD before. The easiest way I've found is to actually sit down with them and help them make their character. Let them build it to their concept, but explain what you're doing and why, and give some brief explanations of how things will end up working when they are playing , but don't get too into it. Do this with each player individually within a week before you start the first game. At the start of the first game, run it like a videogame would. Set up a sort of "tutorial" - something that will show them how to use skills, which dice do what, and have them get into combat, even make sure they encounter something that requires saving throws, and have your spellcasters actually tell you their save DCs when an enemy needs to save vs something. Also make sure you create some kind of encounter so that each of them gets to use their feat(s). It can be difficult to figure out how to incorporate all this into a single session, but doing so will make it much easier on you down the road.
From there, it's just about answering their questions in such a way that they learn how to find the answers themselves.
Honestly I think the best way to learn is by playing or by watching a group of people play and explaining the action as it happens.