I make my own compost from garden and kitchen waste as well as from grass clippings. Grab a handful and knead it and let it fall through my fingers. This can give some information about its consistency. If wet should be sticky and leave your fingers quite 'dirty.' If dry, it should stick together some, but be able to crumble through your fingers. Also pay attention to the nature of the material. If it seems woody or consists of a large amount of plant stems that have not yet decomposed, it is probably nitrogen deficient and will sap the nitrogen from your soil to complete its processing.
In the wild you can pick up some really good humus from the top couple of inches of the forest floor. If the area is well shaded (has a nearly full canopy from the trees), the ground will have been well covered by leaves last fall (or this fall depending on when you go out to collect). The ground will also have been enriched by the animals that live in or among the trees. You can also just plant buckwheat or clover, or even grass as thick as you can and in a month till (or in a container, churn the plants) under. The lush plant growth you get in a month will quickly decompose and add precious humus to your soil. This humus feeds the bacteria and earthworms in your garden and helps break down clay ("softens" the dirt so it won't clump together) and increases moisture retention.
Speaking of earthworms, go buy a dozen or two from the bait store and add 4 or 5 to each container. Also add them to your compost. These guys are the best at quickly breaking down rotting plant material (they eat a lot more than bacteria in a given period of time). Unfortunately they won't survive a cold winter if they can't get out of the compost bin and hibernate below the frost line. They also need moisture so don't let a bare container of dirt get dried out. If you get a good healthy family of worms going in a container, then you have readily available fish bait, just don't use them all! Not only do earthworms eat humus (decaying plant material) and thereby further break it down, they also aerate the soil by riddling it with their tunnels. This provides easy access to nitrogen for nitrogen-fixing bacteria. It also helps to loosen clay-rich soil so that plants can more easily grow their roots.
Offered by Roger.