with the pentool click to create an anchor point and drag to create the "tangent handles" for the curvature
never try to get it right the first time, tweaking afterwards is way faster.
Tweaking possibilities:
adding and deleting point is pretty selfexplanary
use the convert point tool for the following reasons: clicking on a point convert it to an angle instead of a curved line, clicking and dragging make the curvature again but always with handle symmetric on both sides (so basicly use it in the beginning or when you screwed up and want to start over)
Click to view attachmentUse the direct selection tool
Click to view attachmentFor selection a point of your curve so some handle will become visible, then click with it on a handle to shorten or lengthen it and reposition the angle of the tangent. The handle on the other side will follow the angle but not the length.
Alt+click on a handle a seperate direction of the 2 handles.
Use shift key to constrain the angle while dragging to 45/90 degree increments.
Hope this helped a little allready.