If you have a newsletter, pay attention. The middle of the week is the best time to send. But only by a little bit.
Surprisingly, not a huge difference in open rate between a clickbaity subject line and a non clickbaity subject line. A subject line that's direct performs a bit above a subject line that's cute.
The biggest difference for open rate one word subject lines, not two, not three or more. One word subject lines make a tremendous difference for email open rates. And if you want to grow your newsletter and have it get opened more, send your newsletter out once a week.
Consistency is the biggest driver.