It's a very good idea to register your website with Google Webmaster Tools. With it you can find out about crawling errors, get notified if your site gets cracked, see how people are finding your site, get a big list of your inbound links, etc. It's probably a good idea to register with Yahoo! Site Explorer as well.
Make sure you have Googleable content on your page. Try this "html2txt" tool from w3c.
Use the Google Keyword Tool to brainstorm keywords that you should include on your website (and/or links to your site).
If you want to write some good off-site content linking back to your own website, try general sites like EzineArticles, HubPages, Squidoo. Of course you may want to do some guest-posting on other Mac-specific websites and blogs.
Press Releases: We've had good luck with PRMac. There are a lot of other general-media press release services as well.