im not an expert but looking at your first painting all the edges in it are hard. You typically want to vary up your edges with some of them being soft where the form curves away from the light, as opposed to everything being hard. Now a robot like the one you’ve painted will typically have a lot of harder edges but there’s still surfaces that are rounded. Try and find some really good reference of mechs or robots from some really high budget films (like pacific rim maybe) where they will have spent a great deal of time and money properly rendering out a robot. It’s the closest you can get to studying a robot mécha from life because well they’re not real. Hope this helps

What exercise or exercises you would recommend someone do every single day to improve?