CREATIVE MARKET: I use Creative Market a LOT for templates for my e-books, meal plans, rate cards for companies, and even for resumes. Be sure to look for one that is in a .docx format before your purchase it! You also get FREE downloads in your inbox every Monday- which is huge.
CANVA: I use Canva to create images if I need WORDS on them. In addition, canva has a lot of FREE images that you can use. You can also set the images ahead of time to be in the shape you want, e.g. squares for Instagram.