Unless there is a legitimate legal requirement for an accurate birth date, I use the date on the Julian calendar. It’s close enough to give an accurate age while being far enough off to not easily line up with my real identity.
I have a variety of catchall domains at my disposal so I make up random throwaway email addresses as necessary.
I assume my primary public email address will get leaked left and right by well meaning novice database developers so I don’t use it for anything of any financial or legal consequence.
Finally, I have additional internet identities (complete with gmail, yahoo, Twitter, FB, LinkedIn, etc accounts) that I've been maintaining since the 1990s that I use for things I don't want linked back to my primary account (all legal, of course).