I scored a 170/170/5 on the test. I agree with the above posters that getting higher than a 5 is somewhat of a crap shoot. You should shoot for a 4.5+ (fine scores for any graduate program).
I'm terrible at timed writing, but I came up with a system that worked for me. Here are a few tips:
1) Use a consistent essay structure, no matter the prompt. For example, for the Analyze the Issue essay, my essay always consisted of: 1) intro/thesis paragraph taking a hard stance on the issue but acknowledging the potential for situations in which my position didn't hold; 2) body paragraph supporting my position with example; 3) second body paragraph supporting my position with different example; 4) body paragraph acknowledging my position isn't foolproof, usually starting with "This is not to say that" or "And yet"; 5) concluding paragraph restating thesis. No matter my response to the issue - whether for or against - I always used this structure.
2) Have a stock intro/thesis paragraph that you can use for every prompt. If you know the structure of your essay beforehand - if you know, for example, that you will have two supporting body paragraphs and a third taking the contrasting view - you can come up with a general intro that sets up the essay, one that you only have to modify slightly for each prompt. Doing this will save you time and make sure your essays consistently start on a strong, polished note. Aim to have brainstormed your examples and completed your intro paragraph no more than five minutes into the section.
3) Don't attempt to write perfect essays! Remember you are being graded as much for length and fluency as for intellectual content. As long as your ideas make sense and are written well, you'll be fine. I like to compare GRE essays to a topical debate with a friend after too much alcohol - impassioned but perhaps a little thin.
Hope this helps. Good luck!
EDIT: Rereading your post, I see that you weren't really looking for general advice haha. Like the above poster mentioned, personal examples are great! I wouldn't worry about using "I" too often. Likely you will be using "I" only in the body paragraph with your personal example, which is fine.