Having covered the reasons for why artists write artist's statements in the "Artist's Statements- Why Write One?" post, here are the three primary factors that I think makes for an effective one. (Please note that I don't think that there is a particular formula you can follow for this, as part of what makes for an interesting artist's statement is the personal writing style of it's author.) 1. Write a piece that complements the work, rather than explains it. This approach provides additional information to the reader that cannot be found in the work itself. The writing therefore can give your audience a greater understanding of your goals and motivations for creating the work, and help them gain further insight into it.
2. Use appropriate, direct language that clarifies rather than obscures what you are saying. In other words, don't use "artspeak" jargon!!! Here is an article that beautifully explains how annoying and pretentious you can sound if you do. Although the article cites galleries as the offenders, they are often use the text that artists provide to them.
3. Write in your own voice. Don't try to sound like someone else. If you love to write creatively, then use that skill. If you are more of a keep-it-simple-and-direct kind of writer, then write that way. Being yourself in your writing will ring true for the reader.
I honestly feel that if you use those three points to guide you, your chances of writing a statement that can serve the purposes outlined in my "Artist's Statements- Why Write One?" post are going to be greatly increased.
There is way more information to be found on what makes for an effective artist's statement. I particularly like the advice found in this article by Joanne Hurley and Kate Ware.
More on artist's statements in a later post.