One of my favorite "green" things to do is to compost. And while there are numerous "technically correct" ways to compost, I do it the simple way.
Here's my method.
Toss veggie waste, coffee grounds, tea bags, etc., into a stainless steel bowl or other container. Empty that bowl daily in a pile somewhere in the garden. (If you don't empty it daily, mold will grow...that's up to you but I don't like to do that!) Now and then shovel a thin layer of soil over the plant material. If the summer is dry, give it a good shower with the sprinkler. The microbes who do their work need a bit of moisture. If you find a stray earthworm or two in your garden, toss them on the pile, too. They'll burrow down and enhance the composting.
Now and then dig into the pile and turn some of it over to allow the outside areas to get into the composting going on in the center of the pile.
Once you have a sizeable pile, begin a new pile in a new location. Generally it takes a couple months or more to mellow down to compost. In the fall of the year the pile will need to sit there over the winter. By the following spring you should have good compost.
Never add oils or fat or meat products. Use only plant matter (which includes coffee grounds, filter and all).
Be wary of tossing old tomato plants onto the pile due to the diseases that may introduce to next year's tomato crop.
Be wary of tossing in seeds from squash, etc., unless you are ready to spade under the new plants...which isn't a bad idea...they will enhance the pile.
Even in the winter, we'll continue to toss material onto a pile...usually a new pile, letting the first one mellow. But last winter we were unable to do that...the compost was buried under several feet of snow drift. So last winter I was sad to have to toss all that good veggie waste in the garbage! Sigh!
There are all kinds of things you can do to enhance our method...using boards or wires to build a larger pile! Purchasing commercial composting barrels. Using the small "indoor" composting buckets. But I like to keep life simple.
We often compost leaves this way, putting them into a large pile, layered here and there with a bit of garden soil.
P.S. We Never use Oak leaves...those leave are practically indestructible and take a long time to compost. We have no oaks but our neighbor lady does...and we wish the wind did not blow from her direction. Sigh!