calm down chubbi. (thats my nickname fo you) here are some tips:
1. use smoothing. its on the tab where you thicken your lines. turn it up to about 60 percent. you will find it WAY WAY WAY easier to draw than before.
2. use dodge and burn. they are in the tools tab. dodge makes things lighter, or can create a cool sunlight effect. burn is an easier way to do shading, as it makes things darker.
3. use opacity. it is on the edit line tab. (where you thicken your lines) this is how you do a less airbrushy shading. and if you want to know how to correctly shade, draw your light first. then draw your light rays. where the light doesnt touch is where you should shade. (example, under the jaw)
hope this helps!