The best kind of 50th birthday wishes, in my fiftysomething mind, are inspirational. In other words, you should write 50th birthday wishes that make the birthday guy or gal feel great about turning 50.
If nothing good comes to your mind, take a moment to read the article, Good Things About Turning 50, to find out exactly what any 50 year old would want to hear from you.
My favorite inspirational 50th birthday wishes encourage the recipients of your birthday messages that, at 50, they have the potential to take chances and live their lives to the fullest.