test live site

Can anyone advise the best way to test a 'live' site without having to go into Maintenance Mode?

Basically I just want to ensure that it doesn't appear on search engines or get listed, and if there is something that is advised it needs to be something that won't be to the detriment of the site indexed/listed when I actually want it to.

For those that might be questioning why I want to do this without using MM is basically to test a Facebook login to see how it works and performs etc.

Thanks

Stephen