Lucio's Grimoire of Lines and Values

[kidult]

Nice stuff you have here, good variety. To add to the above comments, try spend some time tightening up and adding details. These help with giving your image a focal point, something for the eye to spend time looking on. Speedpainting is good for exercising your ability to put down ideas fast but to be more successful at them you'll need to build up your painting skills by doing longer studies and imagery too