Examples might be: Why should my links not be 'click here' when that's what you do? Why is it not enough to give a telephone number and email address on a contact page?

Those nifty simple sentences that make the difference - examples might be: how do I ask users not to opt-out, or to encourage them to pick a safe password, or reassure them about giving us their details.

What information is needed on a contact page? In what order? What call to actions are required? How do I ask for it nicely? Hiw do I reassure users about my intentions?

We have a homepage and an about page but is it a sign in, sign-in, or signin process? Or a login or log-in? And what do users call it, a menu or navigation? Checkout, check out, or something else completely?

I want to know how to write well, but also converts into sales or another action I want the visitor to take.

Editor: This would focus on how to construct 'calls to action', and helping users take the next step.

Often clients farm out the writing of (micro)copy to their graphic designers, who frequently have little experience as their expertise is in crafting effective visual design, not usable, useful interaction design, forms, and flows (like checkout processes). I find it is often hard to convince clients to spend money on writing microcopy, getting it right, and understanding why it's important - or in fact, that it can be a lot more important to their bottom line than the graphic design.

Some sites have links like "My Photos/Account/Profile" some use "Your Photos/Account/Profile", which should be used, and in what circumstances?

Examples might be: explaining email address changes, describing common password entry mistakes, what doesn't help and why, how to write errors for inconsistent entry, explaining captcha and similar.

Are there any specific considerations we should maek for older users and younger users?

Maybe you dropped English like a hot potato in favour of Art or CS and now you can't quite remember which side of the quote the comma goes, or what you hyphenate.
So a simple primer and reminder would be great, thanks!

Not just a style guide, please! I want to see articles from different authors on topics like interaction copy, microcopy, sign up forms etc.

email, e-mail - tomaytoh, tomartoh?
Skype, Skyping, Skyped etc?
I tweet, you tweet, they tweeted, we tweetered?
We are making up words like they are going out of fashion, so perhaps a section to debate and get some consensus?

For short error messages and guidance, your thoughts on writing 'personable' copy without overdoing it. Hootsuite seem to do this well but I imagine its not an easy balance to achieve -- AM_Doherty

Instead of lorem ipsum what can I do to encourage my client to start creating content. How can I design and develop for actual content in mind

Examples might be: Describing the right card number, explaining a billing address, explaining a card decline and what to do next.

Editor: Well, maybe I'll find a way to include it ... ;-)

A lot of "You've done it wrong" messages (e.g. on forms, etc.), can sound cold, and may well put off the less confident user. How to make these friendlier to build a sense of confidence in the user.

I did some work for an online newspaper that caters to a high-literacy audience and, in the process of doing that project, I compiled a guide of web writing tips from various studies by Jakob Nielsen. The guide is at: http://www.reportla.com/non-cms/web_writing.html. Feel free to take whatever you want!