As a medium, photos are by far the most engaged-with content on social media. The entire founding of the platforms of Instagram and Snapchat speak to that. Facebook itself encourages administrators of pages to post more posts with photos. It's said that a photo speaks a thousand words, in part, because people see and process them with an immediacy not possible with text or video. You instantly have a feeling when seeing a photo.
There's a rarely spoken-of key to helping drive even more successful engagement with your photos, and it's almost counter-intuitive at first glance. Whenever you post a photo on social media that you're hoping to get a good response from - take a moment to see if the photo looks good small, seriously. Many people take the time to make sure their photos looks good large - and all the fine details are exactly as they want - and you absolutely should, but if a photo can't be understood on a smaller scale, those details may never be seen. If it's not worth viewing, it's a lot less likely to be reacted to, commented on, or shared, and may end up being passed up entirely.
Consider that many of your followers are viewing social media on a small device, with a smaller screen, likely in the midst of doing three other things. If a photo doesn't look intriguing enough to be understood at 400 pixels (or sometimes far less), you may be missing out on engagement that you could've had with a more appealing photo.
Before you post, take a look at the thumbnail of the photo and see if you'd want to view it larger.