In my opinion there is no other product more important than the right pair of shoes. The wrong pair can be clumsy, painful, and even dangerous if they don't grip the pedals easily. I just received a pair of Toms as a gift and they are certainly not the shoes to ride in; flimsy, no support, and soles that slip off the pedals make them very bad for even short and relaxing rides.
The right pair of shoes I have found are Simples. The pair I have offer great support and are extremely comfortable my 30 minute commute. They are made from a considerable amount of recycled material including used water bottles, old inner-tubes, and old car tires. The rest of the materials usually come from certified organic operations.
The fact that the soles on my pair are made from used car tires makes them grip well and they are thick enough that my feet are still comfortable after 30 minutes.
The right equipment to carry things in is also important. For a very long time I got by using an old day-pack, but this was troublesome just because of the bulk, it not being easy to get into, and the fact that my back would get excessively sweaty when using it. I switched to a messenger bag awhile back, which was better, but it was heavy and cut into my shoulder.
Now, however, I have a better messenger bag that I really like and is very useful. My fiance bought it for me in Seattle, and after using it for a few days I already see its benefits.
The bag is a made by Alchemy Goods and is pretty unique when it comes to messenger bags. Made from used bike tire tubes, which is a cool idea for a product the cycling community uses. I know I've blown plenty of tubes in the last few years, and I always take them to the local bike shop to be recycled. To think that one of my blown tubes goes into making this product is really interesting and definitely adds value to the product and a connection to it. To actually see what your recycling can result in is a good feeling.
In terms of utility the bag is great. Light wieght and water resistant, it makes for a good bag that can carry a lot of stuff and be comfortable doing it. The pockets are very limited, and the inside is basically one big space, but that just means less material used and more space to cram things in on your commute.