How do you estimate what the pen tool will do in illustrator?

I know how to use it for the most part, but it's so hard to determine exactly where it will go. Are there any guidelines/general rules of thumb to follow.How do you estimate what the pen tool will do in illustrator?
It kinda depends. If you want just straight lines, then just clicking along without any drag will do. If you want to do curves then click on where you want an anchor point to be, then while holding down your mouse, drag along till you get what you'd like. If you release and you don't like how it turned out, then just keep going along and you can edit the shape once you're all done by selecting it with the white/clear arrow tool