I guess the main message here is just to keep it professional, not sloppy, and it doesn't have to be complicated, you can keep it simple.

I bet many of you with websites have had emails from 'wannabe' VAs with the most appallingly written emails begging for work from you. I know I have and sometimes I write back nicely explaining that even if I wanted to give them work, I couldn't because their written email didn't give me confidence in their abilities. I had one guy get really upset and email me back saying he already does work for doctors and it's good enough for them - seems he does a lot of copy typing. But the others have usually thanked me for my comments in their well written replies, simply because they've taken care in what they've been doing the second time around.

Kind of like - do you turn up for an interview dressed in your worst clothing or do you turn up looking your best to make a good impression?

Writing emails, participating in business type forums, etc should be viewed the same way.