Ghost is getting better with image uploads, though I'm finding that managing them externally is much easier.
Normally you can just directly upload an image when you write your blog post and it works fine. Sometimes, you already have an image and you'd like to just link to it. Ghost currently doesn't have an image search, so I don't know what the Url.
Instead, I've started keeping all my images in a folder structure on OneDrive. I can build out the folder structure how I would like. It allows me to reuse an image for multiple posts as necessary
Sharing an image on OneDrive
To share an image on one drive, just add it to the folder OneDrive share on the hard drive.
Next, grab a link to the shared image by right clicking on the file and selecting the 'More OneDrive sharing options'. From the menu, you can select the Embed option where you can select the image size for sharing.
Copy and paste the link into your blog post.
Backup the Ghost blog
When you need to backup the Ghost blog from the admin console, you'll be able to just use the export feature and not worry about backing up images.
Hope this makes your blogging a bit easier.