Hey Ruben!
While your folds and draping looks reasonably accurate, I recommend you pay close attention to the general light scheme of your source. For instance, that model with the green shirt, your rendering does not match the lights on the skin!
There is a pale blue bounce light that should be coming from the left, forming a core shadow in the 3/4 axis, and some warmer light coming from the right. Try de-saturating your overall base color, which allows you to go more vivid around the highlights.
Adding bounce or ambient light within a shadow shadow shape is an extremely satisfying part of rendering - you're missing out on the fun!