Your job as a professional photographer is to bring back images that your client can use. Not just use, but exactly what they asked for.  In order to do this there are two important aspects to consider.  First, you have to understand your craft well enough to be able to create the images.   And secondly you need the tools to make your vision happen.  Here are the major tools that we use:

Full Disclosure:     I am an affiliate for B&H and ThinkTank Photo.