I don't have images to share, as they are often specific to the customer/company. But I have some tips that might be useful:
- Always follow the visual identity of the company you are working for. This helps users understand where they are and makes the experience more intuitive.
- Choose simple images, without many details, as they will be displayed in a very small size and will lose visibility.
- Qlik app and sheet thumbnails must be 8:5 images, otherwise they will be distorted.
- For app thumbnails, you can think of colors by streams.
- For sheet thumbnails, a printscreen of the sheet itself works very well, as the user naturally tends to store a "photo" of the screen in their head, so when viewing the thumbnails they will navigate in a very intuitive way.
Furthermore, in this link you will find a tool for creating thumbnails using the icon + text pattern. Although extremely useful, for future maintenance (creating new tabs, or changing names), I suggest you use some simpler software.
As incredible as it may seem, Power Point ends up serving me very well. There I can modify the slide size to meet the 8:5 ratio, I can easily add and position texts and icons, and I can even export all slides as images (png). Furthermore, pptx serves as a repository for thumbs, making it easier to maintain them in the future (I've included an example in the attachment).
Hope it helps!
