What is the best thing to put around tomato plants?

What is the ideal material or substance to surround tomato plants in order to enhance their growth and health? Is there a specific type of mulch, fertilizer, or companion plant that has proven to be particularly beneficial for tomato plants? What factors should be considered when selecting the best thing to put around tomato plants, such as soil type, climate, or pest control? Is there a recommended method or process for applying this material or substance to the tomato plants?