[Anjelina]

What are the different ways to keep a site out of Google’s index? Which do you use and when?

[MSL]

 I don't keep anything out of the Google's index.

[SEO]

Robots.txt.

And why do you want to keep it out?! A whole site keep out of the Google's SERP?! Why then you need this website?!

Whatever...

[sinelogixtech]

Keeping Content Out Of Google’s Search Results From the Start:
-> Require a login to access the information
-> Use the Robots Exclusion Protocol to block search engines from crawling and/or indexing the content

Methods For Keeping Content Out of Google’s Search Results That Don’t Work:
-> Not linking to pages
-> Using the nofollow attribute on links to pages
-> Putting links to pages in JavaScript or Flash
-> Placing content behind forms

[durga]

What are the different ways to keep a site out of Google’s index? Which do you use and when?

may i know why you want to keeep out side of google index

[SEO]

Yes, that's very strange. If you want to keep it away, just don't upload it online. 

I'm wondering, too...