I've only recently migrated to a hosting provider which has enabled me to have preview links, but I'm not a big fan of letting customers forever see a site I'm working on when they've had the chance to review it once. Enter Coming Soon Maintenance Mode, so simply to use, just upload and flip the switch and you can password protect it in seconds. I tried it and managed to in 15 minutes (half of that was my internet speed), and can't believe how well it worked. It does what it says on the tin and comes with even more extras I haven't yet been able to use such as custom urls, and other rule logic to do.
I've loaded up on tier 3 and recommend it as I can see adding these to my paid plans as a sellable addition. Highly recommended!