Audience, purpose, and design are all key to successful writing for, among other things, structure and style. From the reading, I have learned that audience, purpose, and design can be varied to make your writing more sophisticated. Nevertheless, audience and purpose are the most significant building block for my writing.
For an audience, I have targeted my 'real' type of audience in the past mainly because I have had to get a grade. However, with the real audience in mind I have been able to build an introduction. Without an audience to target, it's hard for me to write a thesis so I need to at least think: "What's the teacher's point of view on this topic? Am I taking the opposing view of it?". I see now though that I can add another aspect to my audience by thinking of the 'intended' audience.
The audience helps me with my introduction but the purpose is what drives the rest of the pieces I write. The evidence I have to pick has to be liked by the audience (for example: if the teacher wanted 3 main points then I need that) but I also need to have the evidence relate directly to the purpose of the paper. If the pieces of the evidence don't link to the purpose then the paper won't have a clear point. Lastly, I like to think of the purpose when I'm writing up a conclusion because it helps me answer: "Why did I write about this?" and that in turn helps me with structuring the conclusion.
Overall, I feel that audience and purpose have had a significant influence on my writing but I need to think of other aspects of the audience and purpose to write about and consider.