Amending refers to changing the condition and function of the soil, rather than adding nutrients to it (which is known as fertilizing). The conditions that really matter are drainage, retention of nutrients and moisture, density, stickiness, and pH.
Examining your options
If your yard has any use for soil, composting is a huge win for you. You can save money by reducing the amount of kitchen waste you send to the curb and getting a high quality soil at no cost. Very little time and effort is needed to set up a composting system. Find the one that works best for your household below.