Yaaaasss! Using the selection tool was going to be one of my first suggestion!
And wow your lines look really smooth.
The way you shaded is great, especially considering you were scared a few days ago
The main thing I'd work on is being more sensitive to the light environment.
When the light is bright, then the values are light. If the light is weak the values are bleak. OMG, teacher humor.
Also, never never never use the white in the upper left corner.