Security steps for online family photos

I’m building a website for my family photos. Short of handing
out IDs and P/Ws to guests, what steps can I take to make my
website invisible or nearly invisible to unwanted guests?

I figured I’d start by not putting our surname on any of the
pages and not having an obvious domain name but what are
other techniques could I incorporate for making the site
unsearchable for example?

Thanks for your help.