Lessons learned?

It's been about six months or so since I published Crystal Eyes (still available at all good eBook retailers!) and it's been an interesting experience. Sometimes discouraging, sometimes uplifting.
When I first did it, I thought I went in with a realistic view of what to expect. It turned out that my "realistic" view was rather optimistic - whilst I knew there would be plenty of other novelists doing the same thing, the sheer number of them that I found, all doing the same as thing as me, was somewhat sobering. Most of the book promotion is done on Twitter and resembles an arena full of people, all shouting more or less the same thing but all trying to get their voice heard. It can get a bit depressing at times!
One thing I've not really learned is how much to push it. I try to only send out a couple of book plugs a day as I don't want to be a spambot, but I wonder if I'm doing it wrong. I see other authors sending out three or four an hour, sometimes more - should I be doing it more? It's my personal Twitter account, I don't want to annoy people who follow me but is that what's needed to sell books? And then there are others who direct message with links to their book or website. I've never done that and always been of the opinion that doing so is obnoxiously pushy, but does it work?
That's a genuine question, by the way - let me know in the comments if something like that would actually work or if it would have you reaching for the Unfollow button. I'm still not going to do it but I am curious.

Another lesson: Prologues are bad, m'kay.
I wrote a lengthy, scene-setting prologue for Crystal Eyes. I ummed and ahhed about putting it in, and even thought about keeping it out and releasing it as a free to download novella, but in the end I included it - this was, I think, a mistake. It takes far too long to get the actual story.
There's some evidence to support this - the Smashwords website allows downloads of a sample and lets me see how many samples have been downloaded, and how many have been sold. There are many sample downloads but very few of those result in someone actually buying the full version. I suspect this is because the prologue puts them off.
I'd be interested to know if this is the case - again, let me know in the comments or via the contact form if you found the prologue hard going or off-putting.
By the way, my next book (humorous fantasy novel with dragons and such like) is straight in to the story, no messing about!

Another thing I've learned, I need to post up more blogs. Going to try and do one a week from now on.