Q:

How is a good answer framed? 

I am used to blogging, so when I answer a question I often reference previous answers.  I just noticed that that is not a good practice here, since the answers change order, depending on the votes. ( I had said I disagree, meaning I disagreed with the previous answers.  Then my answer was moved to the top, so it looked like I disagreed with the question somehow.  I have edited my answer.) 
So I see one non-obvious principle.  Don't reference other answers implicitly. ( If it's important, can you provide a link to the answer you are referring to?) 
In case the question gets edited, the more self-contained your answer the better. 
What are some other principles you've learned as you've written things on SE sites, for how to write your answers well? 

A:

Throughout my college career, I have found it beneficial to outline the question asked at the beginning of an answer.  Not only do I have to restate the question to make sure I understand it, I also am able to take up more space on the paper with my answer! 
I believe the practice carries over to SE as well, though only for the first reason.  When writing a good answer, restating the question so your readers are on the same page as you is beneficial.  Many of the questions asked here have multiple parts to them with one underlying theme.  If you were to just start answering without giving your reader a frame of reference, it could be quite easy to become lost within an answer. 
I'm not sure if referring specifically to another's answer is a good practice within an answer.  If you agree with their answer, you upvote it.  If you mostly agree, comment.  If you disagree, well, that's why you're providing another answer.  It could be helpful to state why your answer is different from the other answers, but that can be done without specifically referring to another's answer. 
I feel that many of these issues will be resolved simply with maturity of the community and some helpful guidance from the moderators. 

A:

Excellent question!  In the early days of Stack Overflow (before there were comments!),  answers regularly referenced each other.   (My top-voted answer still bears the marks of that practice.)  But it quickly became obvious that answers work best when they are reasonably self-contained.  This is why you might occasionally see complaints about link-only answers.  As you say, referencing position makes little sense when answers may be moved around by voting. 
If you want to reference another answer, the usual way to do it is with a link.   During the private beta, that's a little harder than normal since the share link is removed from the interface.  But when the site goes public you will be able to copy a direct link to the answer itself:

Then you can use Markdown's link syntax:
Building on [UnCleJack's answer](https://parenting.stackexchange.com/a/11828/4521)...

Depending on how much you want to add, you might be better off suggesting an edit to the answer instead.  It's a judgement call, but the more you have to add, the more likely you should write a new answer. 
When answering, I have two audiences in mind:

The asker, and
The future readers. 

As a rule, the asker will be less and less important as time goes on.  Many questions I've asked are no longer interesting to me, but continue to help future searchers.  I try to answer starting from specifics and expanding to generalities:

In your situation, X should work well, but you might also consider Y and Z when similar problems arise. 

That sort of thing.  
Blogging turns out to be good preparation for answering on Stack Exchange.  I sometimes pretend that the question was an email that I decided to answer publicly.  Other people might be answering too, which is interesting.   But my answer should stand on its own.   Obviously it's critical to answer the question directly.  But there's also room to address the bigger picture.  Ultimately, we optimize for pearls:

Incoming questions are a universal constant, all around us in countless billions.  But answers—truly brilliant, amazing, correct answers—are as rare as pearls.  Thus, questions are merely the sand that produces the pearl. 

So be careful not to let other answers distract you from creating timeless, complete, and expansive answers.