I think that I am very prepared in April Fools not to fall for pranks, although I may be vulnerable if the right stimulus comes. For now, I have been very sceptical about every strange thing I read on this date, and maybe not so much in other dates.
Every year, I visit the subreddit /r/AprilFools to check for a user-provided list of the day's pranks. I enjoy the day a lot, but seeing as I'm too accustomed with the style of the pranks, I have unfortunately, or fortunately, not fell for any in a long while.