There's a couple of things you are going to need first.
The first of which is going to be your keyword phrase. There's a 22 character limit on this. So long tail keyword domains won't work.
Create a free email account for use with backlinking. Tumblr may ask for you to confirm your address. When i used it to try things out, unsure if it would still work, it was mail.com I used. That way it isn't linked to any of the emails that I use on sites like this one.
You can find other free email account providers at
http://email.about.com/od/freeemailreviews/tp/free_email.htm
It will also help to be using seoquake.
For SEO things this is something I think every marketer should have. After all, it's free
This is for later as it helps identify which pages have the page rank you are looking for.