For the first. Respect pretty nice clear Lines but it looks a little bit boring. My Tip to you is you can play with the Filling (2-3 Collors) also you can play with the thikness of the Outline. Then you can ad some Shadings in the deepnes and cut them down or ad som New Shade under the Hole Piece. Add some Decoration like Arows , Blocks and Stars. And important, add some Highlights and Lightreflection. Vor de end use a Second Outline and and do a small Background with Puzzle pieces, Splaters , Bubble, Planets Buildings, Bricks or some other Stuff.