I disagree with the idea that you should go easy on new players entirely. I think you should always play your best, especially when showing someone the game. Otherwise you are teaching them bad habits. They are looking towards you to learn how to play after all. Plus, I don't find it fun if someone lets me win, so why would I expect someone else to enjoy me letting them win?
Instead, I would recommend playing your best, but take it extremely slow and explain everything in great detail. Explain what you are doing, why you are doing it, what you are planning on doing in the future, and what they might do in response. Be completely honest. This takes away a lot of the surprise elements of the game, but allows you to still play your best and for them to understand what's going on and how they can compete against it.
They will still probably lose, but they should feel like they understand the game and that they have a chance to beat you if they stick with it. The reason creaming newbies might turn them off of a game is that it can make them feel overwhelmed and like they'll never get the hang of it because they don't understand what happened. But I don't think anyone expects to be a master of a strategy game the very first time they play it. As long as you make sure they understand what's going on, they should be fine with losing their first game (or three), and will probably be excited when they finally start surprising you and closing the skill gap.