Start where you are with what you have. Fortunately anything that was once alive will decompose in the presence of air and moisture. We can affect the speed, space and smell of the process, but given time, nature will do the job for us.
Some of us regard compost as a valuable input to our garden. Others of us as a way of disposing of organic matter from our house and garden. Fortunately we can achieve both.
If we have a mixture of ingredients that are fresh, soft and moist (usually green, but coffee grounds and tea bags are one exception) and dead, stiff and dry (usually brown) the twiggy ingredients keep the pile open enough for air to reach the soft ones. It also allows excess moisture to drain away. We can store the dry ingredients (cardboard, hedge prunings, fallen leaves) to mix with the fresh ingredients such as lawn clippings.
I’m making compost from filling a bin with fresh flax leaves only and watering well. I’m making compost from agapanthus leaves and flower heads in two bins, also watered well. The flax will take a while but both will provide useful inputs to my garden.