Know When to Leave Well Alone
I've fallen for a huge number of fads and tried all manner of strange products and gadgets over the years, and many of them did more harm than good. The biggest lesson I've learned is that if something is fine, leave it alone as much as you can.
I am eternally grateful to my grandmother, who told me that under no circumstances was I to tweeze anything other than the very obvious stray hairs from my eyebrows. Now, as so many of my old school friends struggle with over-plucked '90s "paisley" brows that won't grow back, I still have a decent amount of hair to work with to get the current power brow.