There are countless ways of making compost, each as enthusiastically championed as the next. This is mine. Gather together the plant material to make as big a heap as possible. Chop up the larger pieces into lengths of 10 to 20 centimetres (it's easier to do this while you are pruning and cutting back in the garden). Or hire a shredder if you've a big load.
After laying a 15-centimetre base layer of twigs or other slow-rotting, aircapturing material, build up the heap. Aim for a composition that is approximately two parts dry, brown material (shrub prunings, plant stems, withered herbaceous stuff) and one part green, sappy material (weeds, grass clippings, kitchen waste, fresh leafy matter). Mix the green and the brown together and water the heap thoroughly as you go.
If you have access to fresh farmyard or poultry manure (not dog or cat faeces) add a layer every 25 or 30 centimetres to help speed things up. After a final hosing, cover with old carpet to keep the warmth and moisture in. In a few days the heap will heat up dramatically and give off a sweet, steamy odour. In a couple of weeks, turn the whole mound out into a second container, or rebuild it again in the same space. This promotes another burst of microbial activity. It also gives you a chance to see if the mix needs more moisture, more nitrogen-rich green matter, or more carbon-rich brown matter. Depending on the speed of decay, and the time of year, compost is ready for use within three to 12 months.