BUBBLES!!! ok now that I got that out of my system, this is pretty cool, I love the floating feeling. Perhaps combining this sense of realism with the aesthetic style that you usually draw. That would be interesting/creative I think .
I'm sorry to say this, mate, but this is among my least favorite drawings that you've done. :/ Not because of content, but because of a lack of your usual flair. It's by no means a bad picture, but it's not as good as what I've come to expect from you.
Just like traditional art you learn how to use the tool. It's something you have to tinker around with yourself, as its hard to just describe in a comment. Download trials of whatever vector program you want and start toying around with the program.