A question was recently asked on meta to solicit suggestions on how to develop answers with a "polite and academic tone," with an eye toward helping users to better understand the purpose and function of Christianity Stack Exchange.
The format adopted in that question, as suggested in the comments -- community wiki with one suggestion per answer, so that each suggestion can be voted on independently and edited with ease -- seems like it has the potential to be a great resource for the community, if enough users contribute. This question is asked with the same motivations, and has a somewhat broader scope:
What qualities do the most effective C.SE answers share?
(A definition of "effective," for the purposes of this question, is defined in the following section).
Some dispersed information is already available: the help pages provide some succinct directives, there is an excellent meta post about developing "good, supported answers," as well as some info on "good subjective answers." See also: (1), (2). It might be useful to collect the best content found in these various questions and summarize it in one post here, for future reference.
Of course, different users have different writing styles, and there are many ways to write an effective answer. But the most useful answers surely have several qualities in common.
If you have contributed answers that the community has deemed highly effective, what are some things you keep in mind while composing your answers?
If you read a lot of C.SE content, what qualities have you observed in the highest rated answers?
If you ask many questions, what qualities do the most helpful answers have in common?
For the purposes of this question, let "effective answers" be defined as those answers which:
Comply with C.SE guidelines as detailed in the help pages: on-topic, considerate, focused, factual, free from basic issues of spelling and grammar, etc.
Are highly upvoted by the community.