Use of Pen Tool

I am working with Adobe Illustrator CC 2014

As I have been trying to teach myself the Illustrator program, I came across something that really bothered me and messed with my mind: the pen tool. I cannot seem to control the centering of the curve that results from 'holding down to create a new anchor point.' I would appreciate it if someone could help me out in figuring out this portion in the pen tool.

Also, how would i smooth out the point where a curve begins of a branch of a line?

Also, please post any tips you have for 'mastering the pen tool.'

Thanks in advance.