This is addressed to all the fraidycats that don't think their skill is up to snuff enough to write a tutorial:
There are no new ideas in retouching. Well, that's not true. But there are very few new ideas in retouching. Wait, that's not true either. Ok, there are lots of new ideas in retouching, but that's not necessarily what we're looking for in our tutorials.
New ideas are great, and if you have them, by all means share, but that's not the point of our tutorial section. At least not the main point.
Anyway, think back to a tutorial you saw or a chapter you read, or a thread you followed, or anything at all that gave you that little light-bulb-over-the-head a-HA! moment about something. Re-visit it. Study it. Now close it and put it away and begin your tutorial on exactly the same thing, using your images and your screenshots, explaining it as you understand it.
That's it, it's that easy. Of course, if you've invented a totally new technique, skip that last paragraph and move directly to publish.
Have I mentioned it doesn't have to be your invention or even your original demonstration method?