I know some of my designs can be quite a torture test for some people. 95% of the issues are related to improving the bed adhesion and dealing with warping/curling. Also, some may find issues with brittle links easily breaking, which is caused by underextrusion on small perimeters.
This has a simple explanation: The articulations I use have small parts with ~45º overhangs. Theoretically, they are perfectly able to be printed without issues. However, as the filament cools down it shrinks slightly and causes it to curl up. As a consequence, the nozzle may collide with the printed part and detach the piece if the bed adhesion is not strong enough.
Fortunately, there are some easy tips that may solve almost all the issues.
Also, I strongly recommend testing my free designs before purchasing the more complex ones. They may help you to understand better your printer, and will teach you a lot about the printing process. You can find them here.
All the following tips are just from my experience and may not work for everyone. Keep in mind that I'm just trying to help 😉