Commercial photography is a broad umbrella term but for the purpose of this article we will consider any photography one is paid to do for producing photos meant to be used for commercial purposes as commercial photography.
In general, you are required to have professional equipment. You should have the right cameras, lenses, lightboxes, light tents and anything else you need to capture the perfect shot. If you are required to go to a location for shooting then make sure to be there at the agreed time and bring all the required equipment. While discussing with the client, make sure to include the time you would need to set up your equipment into the timings. If you need 30 minutes to set up all your cameras and lights then you better make sure you ask for 30 minutes extra in the contract. Most importantly, you need to rely on your creativity. Your clients will most probably give you a clear or fairly approximate idea of what they are looking for but there can be times where you need to put in suggestions or ideas which would make the shoot go better. Perhaps the lighting could be better or the composition of the subjects could be arranged differently or anything from the tiniest detail to a major aspect of the shoot could be altered.
A good thing to keep in mind is to get a clear idea of what the client wants and to set a reasonable price for your services. Accordingly set your prices to shoot for small businesses which will use the photos on their stores or on small scale purposes and for large businesses, on the other side of the spectrum, who would use the photos for billboards and such.