Down and Dirty SEO

OK, I'm kinda new to this so, is there a quick set of down and dirty suggestions to help me understand and manage SEO or am I in for a "real learning experience" from the get go? (HEY, I saw that 'OMG, no!" eye roll)

I've seen several people are using All in One SEO with Atahualpa. My understanding is that this plugin automatically populates the SEO fields (if that is the correct terms) making this a good "beginners" start at getting the site effectively seeded in the search engines? Then I can go back and tweek the page and title content if I want better results and continue to let All in One SEO do it's job?

And this is as opposed to going through the entire site and manually setting all SEO content in the pages and in any post tag lines, using my best judgment (which is based in ignorance)?

I've been told that good SEO is a highly paid art, particularly if you're going against highly competitive, intensive information sites like attorneys pages competing with Findlaw and each other, etc. I was also told that SEO mismanagement can result in the site being blacklisted as spam for a long time.

I REALLY don't want to screw up an attorney's site.

Any help please and thanks?