Create Then Iterate
Prioritise speed over perfection when it comes to generating organic search growth. It takes time for new content to become indexed and start performing. For this reason, the quicker you can publish content the better... come back and improve it later.
For images, this means leveraging royalty-free imagery initially to add some visual appeal with minimum effort. Undoubtedly, unique imagery will always with the day but they're also time-consuming to create. Publish your content now with royalty-free images and then replace later with bespoke visuals.
Finding Relevant Royalty-free Images
There are a growing number of free to use image repositories online that require no attribution (although you still can). Some of the best are:
The problem is that not all of these websites have a great internal search feature. This means if you go to each of the websites directly you might not find what you're looking for... even if they have relevant images!
The solution is to use Google's site: advanced search operator to leverage the power of Google to search for relevant images. For example, a search for images of "red and yellow flowers" on Unsplash would look like this.
The big benefit of searching this way is you can be a lot more specific with your search and still expect relevant results (if they exist).
Site: Search Links
The following links will open a site: search in Google for each of the above image websites. All you have to do is type your search at the end and you'll have the best source of relevant royalty-free images on the internet!