Swipe ideas from some of the best Facebook ads
An excellent example of the use of a show-stopping picture that stops people scrolling and gets their attention, even before you read the copy.
The use of emojis also has the same effect, and while I'm not a huge fan of their overuse, the balance is just right.
Also note the use of that magic number - 7 - again, which seems to crop up regularly in ads.
The ad's primary strategy is to create urgency and scarcity, which it does very well by placing the emphasis on the fact that this us a limited offer.