Rather foolishly, I have been developing my site on a live server (with VCS don't worry), kind of using it as a portfolio / show off piece. It is far from finished.Recently, I noticed that Google started to spider it, including some of the debug data accessible across the site as it's in 'debug' mode. I'm not sure of the future effects this will have on my site when it is finally released - especially as some pages are just erroring out while I develop and there is some gobbledygook/dummy/blank data on a few pages.SEO wise, what are the best steps to take to not incur any present or future Google penalty? One thing I thought of was to possible disallow spidering in robots.txt, put up a splash page and then setup a decent sitemap when the site is live again.Regardless I am going to setup a development domain somewhere but would like to know the safest way of migrating it down. 
Best way to take down site for a long period while I develop it
seo;web development
I'd do two things:Verify your site in Google Webmaster Tools and request removal of your full site. Remember to undo this when you're ready :-). Keep in mind that this will only last 90 days, so you may have to re-request a site removal at that time.Return 403 (use HTTP authentication) for all URLs on your development site, including the robots.txt.  Returning 403 for the robots.txt will prevent the site from being crawled, so you don't need to block it in the robots.txt file (use the normal robots.txt file that you'd use when you make the site public). Reasons for using HTTP authentication over robots.txt disallows include blocking the site to all other visitors, and making it harder to accidentally publish a robots.txt file with a full disallow :). The latter has happened too many times, even to really large sites. 