If I want to try autosuggestion rather than MILD, in what is it distinguished from autosuggestion? I’ve followed a course self-hypnosis, but MILD has always seemed like autosuggestion to me.
I’ve read that some people imagine stepping down stairs to induce lucid dreams (which I’ve tried, too, without success). Is this a kind of autosuggestion?
Moved from General Lucidness. 
Well, I think this isn’t quite the right forum (Pathways to Lucidity would be a better one, I’d say), but I’ll answer your question all the same:
MILD is basically remembering to do something in advance. It requires quite a bit more willpower and concentration than autosuggestion, which is more of a passive kind of induction method. The difference is in the amount of effort involved on your side.
Autosuggestion is something you can do casually, and at pretty much any time during the day, whereas with MILD, you visualize yourself becoming lucid and really making sure it’s the last thought before you fall asleep. Also, autosuggestion is something that works better if you use it for longer periods of time. MILD generally only works the night you use it, since it’s rather specific.
An example of autosuggestion would be: “I’m going to have a lucid dream in the near future” without worrying exactly when it will happen. You might resuggest it daily for a few weeks, but other than that there’s not much else to it.
MILD takes conscious effort (though not nearly as much as WILD). You have to really set your intention, really mean for it to happen. With autosuggestion that’s actually counterproductive.
This is basically what Stephen LaBerge explains in Exploring the World of Lucid Dreaming (a great source of information on lucid dreaming and one that many LDers are familiar with).
Svenshinan has it about right, Auto suggestion is just suggesting to yourself throughout the day something like “I will have a lucid dream tonight”. It is not an induction method in and of itself, but can be useful. MILD on other hand IS an induction technqiue; you use conscious effort to cause yourself to have a lucid dream. With MILD you can have lucid dreams at will, anytime, any moment. With autosugesstion that isn’t possible, they will be random and probably less frequent.
As Svenshinan suggested take a look at EWLD for further information on the techniques and differences between the two.