H-Bridge vs Motor shield for the arduino
If I were a beginner, I'd go with the Motor shield.

I'm even personaly using the one from DfRobot, which as @Gerben said, is just plug and play.

It also allows you to select the input power for the motors, which can be either from the 5V Arduino pin or from an external battery. This is pretty convenient if you need more than 5V to power up your motors. It can also support 2A of current draw, which is more than enough for small arduino toy cards.

Here is the shield: https://www.dfrobot.com/index.php?route=product/product&amp;product_id=1180&amp;search=2A&amp;description=true