I'm a big advocate for using text overlay to create a "one-two punch." Meaning, you want the Pinner to see a compelling image with an assist of text overlay that makes them stop their scroll. They're into the visual but the text overlay really lets them know WHAT the Pin is about. Essentially what they will get if they click it.
However, many many Pins I see aren't executing the text overlay in the most optimized way. Keep in mind that most Pinners are on mobile so you should always assume that someone is seeing your Pin in their FEED on their phone. Not, a close up zoomed in Pin, actually among all the other Pins as they scroll.
Adding too much text, too small of font, or hard to read fonts (like script) make your text overlay hard to read and can actually just end up looking like clutter and making your Pin stand out LESS.
Pro Tip:I always suggest uploading your Pin and then going checking it out yourself in your phone in the feed and see how it reads. Here are some examples of Pins I have designed. When a brand insists on a lot of text, or a detailed font, I will upload them and show them why that's not the best idea.
Here are some Don'ts:Too much copy, hard to read fonts, text too small, text for the sake of text (vs really supporting the point of the Pin's content)
Here are some Do's: Text is large,text is bolded, easy to read font, text is brief and supports what the Pin content is (it adds value to the Pin's image and aids Pinner in understanding what it's about)
I hope this helps inspire some of you when you're designing your next Pins!
(note: all Pins were designed by me in my role as a contractor at Pinterest and I have permission to share them)