Here are my talking notes from last night. Note that I'm working from n=1, so I'm not an expert. I've just been there once.
* Application essays are not your standard 5-paragraph essays. The goal is to have your child reveal something about who he is that the admissions officers don't yet know. It's all about that elusive thing called voice. Have your child read The Gatekeepers or On Writing the College Application Essay before starting to write (both books are written by former admissions officers). The latter has superb examples of how to edit a piece. Expect 7-8 revisions of each essay.
* Unlike interviews, a great essay probably can get a marginal student in. (According to the woman last night who does college interviews, interviews are really more useful at weeding candidates out.)
* Someone else who spoke on essays pointed out that you should tailor your essay to what is lacking in the other elements of your application. E.g., if your recommendation letters are likely to cover topics X and Y, your essay should highlight something else.
* Think of what's special about your child. You want those things to shine through. Don't preach: show. The point isn't to say, "I'm creative" but have the reader think "Wow, he's creative!" (or thoughtful/resourceful/persistent/innovative/witty...)
* Teens may pore over college web sites and admissions blogs, but they're usually not attuned to meta-messages. Parents can help out here. Do a bit of surfing and point things out that the teen eye is unlikely to see: what is the college really telling you they're looking for? People who want to change the world? Kids who think of themselves as intellectuals? What kind of sense of humor do they have?
* Most teens don’t know (yet) how to spin a negative into a positive. Your child will probably need help reframing “I had a boring, lousy teacher who made math mistakes” into “My teacher was new to the school and new to teaching the course”.
* Writing's a very personal thing, and kids can be uber-sensitive about having Mom or Dad look at their work. Find a way to work effectively with your child on editing. For our family, email was the way to go. Eldest would send me her essays, and I wrote out my comments in an email (not on the essay) and sent them back. This forced me to reflect and synthesize my thoughts, which was a lot better than slashing through everything with a red pencil. Remember to go back through your email and add words of encouragement before hitting 'send'!
* If you're not great with writing yourself, think through who you know who might be able to help with editing. Make sure that your child is reasonably well organized before sending essays to someone else for feedback. People are happy to help, but asking someone to review six or eight pieces, three or four times each, is asking a lot.
* Try to finish the whole application package a couple of days before the deadline and then wait 24 hours before submitting it. This gives you time to let things sit, so when you suddenly wake up at 2am thinking of something that absolutely must be changed, it's still not too late. Also, if you apply to one college early, try hard to get the rest of the apps done before you get the early admissions news. We know one family where the child applied EA to his dream school, but was rejected. He ended up writing his other essays while depressed and feeling like a failure.
Another speaker and I chatted before the presentation, and she said something I think is true: the college application process will bring out all that is good -- and bad -- about your relationship with your child. Whatever weaknesses already exist in your communication patterns will be highlighted. It's worth a bit of forethought to consider practical ways to avoid the usual pitfalls.