Recently, I've uploaded ten eBooks. These eBooks are collections of 100 cartoons from my "It's a Jungle out there!" cartoon series.
The eBooks can be seen at my Amazon Author's Page
The process was actually rather simple because I used the Kindle Comic Creator supplied free by Amazon.
After an easy download, the following points had to be noted. My cartoons are usually, by default, 2360 by 2930 pixels because I draw my panels 15cm by 15cm, scan at 600dpi, then reduce by 60% to put into the template. The standard page on the Kindle is 1280 by 800 pixels. As I wanted to put one cartoon per page, I used FastStone to do an automatic re-scaling of my cartoons to 800 by 993 pixels to maintain the axial ratio.
The covers were done by using a blank template 1280 by 800 pixels.
As I wanted a simple layout, i.e., a cover-page followed by 100 pages each containing one cartoon, the process of creating the book using the Kindle Comic Creator was very easy.
It took me about 2 hours to put the first eBook together, including uploading it to Kindle Direct Publishing. The subsequent eBooks took about 30 minutes each to put together and upload.
Of course, I had all the cartoons already drawn. That is indeed the longest part of the eBook process :)