Edit: Moved at Pat's suggestion.
I'm not sure if anyone needs this but here's some of the rules that I use to get C&C and prereaders. I'm putting this here because no other place fits better.
This was on the previous form and has been revised and reposted.
Getting reviews
First, your writing has to be good enough to start with that someone will not just read it, but stand it enough to comment on it. This requires your spelling, story, characterization, and plot to be at a point where it is coherent.
Admittedly this is a low standard, but it's worth mentioning.
Next, you actually have to post new material. Don't expect C&C if you haven't posted anything recently. People do go back and comment on something that they just found, but more will be inclined if it is new. That's just the way people work.
Make it clear you want C&C. It sounds obvious, but it makes it known that you're actually interested in readers want. Try to be serious. If your readers think you're joking they might not actually reply. May seem silly but I've seen that happen.
And if you get a review reply to it. This lets the readers know that their efforts of commenting are not going to waste. This is especially true if you are trying to get prereaders.
If an author begs for C&C and then complains about never getting it, how do you think that makes the readers who DID give C&C feel?
Do you think that that reader will be inclined to C&C for that reader again?
Remember C&C and reviewing is a voluntary thing. The reader actually has to get initiative to do this. Don't discourage them from doing this by a lack of effort on your part.
Trust is very important here. If a reader feels that their voice is not being heard, then the writer will not get any C&C from them. Never ever mock someone that's giving you C&C. Even if the writer thinks it's worthless don't reply in a harsh way and NEVER mock it in public.
That will do nothing but discourage other readers from reviewing. If a writer says he doesn't like "nitpicking" then say goodbye to getting grammar and spelling corrections. If a writer mocks someone for pointing out plot holes or problems in characterization... the same thing will happen.
This does not mean you have to reply or cater to flames or trolls. On the contrary, they will wreck things. These are best ignored. If especially egregious then one can post a reply.
It goes both ways. As the writer, don't accept comments from someone who is incompetent, arrogant, or annoying. Don't deal with people like that. They are not worth the hassle.
If it's in the form of email. Always reply to it. If it's just a short "That's great write more" thank them for their interest and ask them what they liked about it, and what they didn't.
If they reply (which is highly likely) then you've got more information about your fic. Keep a dialog with them and see what they think. Be polite, but don't push them, they're doing this of their free will.
As for FF.net reviews and the like... you can do the same or if you prefer just reply to the more detailed and better ones. Some FF.net reviews are not practical to reply too. Their system is a pain but if you want to get more detail to your review it's worth the effort.
The key here is to encourage dialog with the readers. Let them know that you are reading their comments on your work. That really helps because the reader feels that their input maters and is having some effect.
This really helps encourage more reviews and comments.
Forums, if properly populated and maintained, can be a very good place for public dialog on fics. Email and Messenger of course work very well too.
Reciprocity is good too. If a writer never gives reviews or comments or detailed C&C to other writers. How does he expect to get writers to review his work? Help whenever you can. Reputation is key here.
A note about author's notes. Do not use that to write a response to reviews of the previous chapter. That is a poor idea and distracts from the chapter. The author's notes should be as small as possible, and only address general thanking.
Email, PM, and forums are all much better ways to respond to reviews.
Prereaders
Now prereaders have a similar etiquette. They are volunteers who comment on your work. However as they do more work and have a greater influence. This necessitates a good working relationship with them.
Now how much influence a prereader has on your story, and even how much of it beyond what is publicly available they know.
Another thing about the prereader relationship is reciprocity. If your prereader has a project of his own that he is working on, then it's implied that you will preread that story.
That can be a drag, and if you have a real problem with doing that be honest and up front with your prereader about it.
Getting a prereader is best done not by asking for one in the end of your chapter but by asking a person who has given good reviews or C&C. Ideally a person who has given good commentary and is able to spot your mistakes.
Of course this person has to say yes when you ask them. Though if they have been an avid reader and reviewer to your fic, then there is a good chance.
You also want a prereader that is more of a 'yes man'. A prereader that knows he is nothing more than a rubber stamp to your ideas will be a lot less involved than one that knows his opinion actually matters.
But for C&C in general dialoging with and respecting the reader is key. If you offend a reader because of your actions then they won't ever reply to you. They might still read it but they'll never comment to you.
Summary
1) Make your readers aware that you want C&C
2) Dialog with those that give commentary
3) Make sure they know you appreciate their effort. Never ever insult, mock, or ignore them.
4) Don't ask for C&C when you're not going to use their efforts. If you want yes-men then say it. Don't whine about a lack of C&C when you have a history of ignoring and not listening to those that give C&C
5) Reciprocate. If you expect to get C&C it helps to give it. Find a forum, a chat room, anything and help others.
Don't just sit there expecting people to love your glorious work
This is for those that give reviews.
1) At the very least say three things: general impression, something good, something bad.
2) More information is always helpful
3) Your time is finite. Only give detailed reviews to writers that appreciate it. If the writer doesn't indicate that he listens or cares about your opinion then drop him.
What things have the other writers here done to help get C&C?