I've long found this process of finding just the right image a bit of a chore to be honest. That's because I do a lot of blogging in the political and news commentary niche.
Since much of that is topical and involves a lot of rhetoric, ideology and quotes, text is all important. While it's nice to include images, not having them in posts seems not to negatively impact them. If they're good and timely, they still get shared a lot. That being my main blogging niche, I've found it a bit of a challenge to get into the habit of including pictures in posts on this blog and others.
Reverse the process
Still, I'm well aware of how powerful paintings, photos and infographics in blog posts can be. So I've been thinking about how to include them without spending so much time finding them. And I suggest this more streamlined method:
Instead of writing posts then looking for images, why not do it the other way around? A picture paints a thousand words, after all. (And that length is actually a good one for a blog post. If it's fairly long it is more likely to rank well in the search engines, remember.)
So, get into the habit of collecting free images that you like and that inspire thoughts and observations. Then write comprehensive posts elaborating on these themes.
Obviously this will save time. It will also make the posts themselves more relevant to the images.
Use photos you've taken yourself
This approach is also a good motivation for taking your own photos. If you have a locally oriented blog (as I do) then it's ideal. You can take photos of local landmarks and write detailed and interesting posts about them. Put the geo-specific keywords in the titles and your posts are sure to rank highly for them.
But you can take photos of objects that can be used metaphorically as well. For example, an apple can symbolize health, nature, or even sin! You can include a photo of a stairwell to communicate the concept of progress, ambition, or raised consciousness. Pretty much everything you see around you can be used metaphorically. When associated with clear and well written content it will be absolutely clear what it symbolizes. And it will thereby complement that content nicely.
So it's a good idea to keep your camera on you. Whenever you see something that can be used in a symbolic way to inspire a blog post, take a snap of it. It doesn't have to be artistically stunning -- just clear and crisp. Doing this will save lots of time. You'll also avoid copyright issues that sometimes eventuate if you use free images from sites like Flickr.