Here is what you need to start with SUP

The absolute minimum gear is a paddleboard and paddle.

 However, there are some important pieces to add to your kit.  

The first is a life jacket also known as a Personal Floatation Device (PFD).   The US Coast Guard considers a SUP to be a vessel, and the law requires a PFD in navigable waters.   A PFD is not required while you are paddling in the surf zone.   

Sunblock and sunglasses are also recommended.

In choosing a board you will need to consider that you are a beginner and choose a board recommended for your skills.  A beginner board will be wider than for general use.  If you are already a surfer, you can probably deal with a more advanced board from the beginning. 

Another consideration is having a board with sufficient volume for your weight.  A board with insufficient volume will ride too low in the water and will be unstable.  You should carefully consider your first board purchase, because it will be the largest expense.   Renting boards or attending demo days provided by your local SUP retailer is a good way to see what suits best.

The paddle is next item of concern.  A high quality paddle can be a real joy to use, but you do not need to spend a lot in the beginning.  A moderately priced adjustable length paddle is a good first choice.   You might want to experiment with the length, and you might have friends or family that will want to see what SUP is all about.  Most manufacturers recommend a paddle length that is about 10” more than your height -- consider this as a starting point.

A leash is can be a useful accessory, but you could delay this for a while.  Once you begin to venture out with wind or in moving water the leash becomes important.  The leash is a line that attaches to the tail of the board and to your ankle.  If you fall off of the board, and you have a leash the board will not get away from you.  A moderate wind can carry the board away very quickly and faster than you can swim.