Sorry, I dont really like them...alot of them are too basic, they look very simplisic, but not in a good way. You should really start drawing with a reference, that helps alot when it comes to drawings. Also, just because its Paint, doesnt mean you cannot add small details. Use diffrent size brushes, its also good never to use the "line tool" They make things look quite ugly...I'll give you a few of my MS paint pics...mabye they'll help you in some way...
Are they "great" drawings? Heck no. But they might inspire you...or something...


Now these WERE done using lines and circles, but I added alot of small details, and used shadows...which always helps...




**THIS INCLUDES SOME BAD WORDS...SO...COVER YOUR EARS...er..eyes..**

Before anyone gets on my back...please, im really trying to help out. And I hope this does.