You understand 3d very well, try playing with the vanishing point just for the fun of it...ie: make it to the top right of the page instead of right in the middle of the piece
your letters have zero flow or style
personally I would say screw colors for awhile and do a shit ton of sketches of just letters first
it looks like you understand letter structure really well, so use the blocks for the letters and extend them a bit, bend them, or play with them however you want
I did a sketch to show phony what I mean, hopefully it helps