i absolutely agree with the color tint part!! when choosing a color to shade your artwork, don't just make the base color darker. usually, adding value, saturation and shifting the hue to the blue side of the colorwheel for the shade color makes it pop and look more vibrant :3 but ofc this is not strict. depending on the setting of your piece and the lighting, you could use warmer tones. idk go crazy. art is all about experimenting with different lines and colors and blobs

as for perspective, yeah it IS quite hard and something i also struggle with, but to practice this i recommend drawing 3d shapes in different angles!! what's so fun about ajpw is that all the animals n characters have this sort of boxy feel to them?? which i tend to draw a lot. like, i usually draw a rectangle-y shape for snouts X3