They just try to get a good ratio of carbon to nitrogen, keep the pile moist and well aerated, and wait until everything looks pretty well broken down. If you want to get a little more scientific about it, buy a compost thermometer. Commercial activators can help raise the temperature in your compost pile by providing a concentrated dose of microorganisms and protein. Other effective activators that can help to get your pile cooking include humus-rich soil, rotted manure, finished compost, dried blood, and alfalfa meal. Unless speed is a priority, frequent turning is not necessary.
Many people never turn their compost piles.
The purpose of turning is to increase oxygen flow for the microorganisms, and to blend undecomposed materials into the center of the pile. After turning, the pile should heat up again, as long as there is still undecomposed material to be broken down. When the temperature stays pretty constant no matter how much you turn the pile, your compost is probably ready. Though turning can speed the composting process, it also releases heat into the air, so you should turn your pile less frequently in cold weather. Make sure there are air vents in the sides of your compost bin.