Greens, Browns and Blues
Whatever your composting technique, you are going to need to know about the three categories of composting materials.
GREENS are nitrogen-rich goodies from the garden and the kitchen, probably the primary reason you have decided to compost. Lawn clippings are the epitome of GREEN, and by themselves, are a big compost problem. Used properly, however, they are a valuable nutrient for your garden. "Using properly" means mixing with at least an equal quantity of BROWNS.
BROWNS are carbon-rich items. At their most basic, they are soil - the soil that comes in with the weeds. But is this enough? You need at least equal quantity of BROWNS with GREENS, and it isn't always that easy to be sure you have enough. Cardboard: egg boxes, corrugated cardboard, packing materials - are all low quality papers which are more beneficial to the planet in your compost bin than in the recycling system. Newspaper works too; junk mail*, stalks and dead leaves too; specialist items such as scenescent bracken, chipped timber, sheeps wool and wood shavings. Realistically it is hard to ensure you have adequate BROWN material in your pile, and this is something on which you need to work
BLUES are the natural requirements for your compost: water, air and soil. Water is necessary - in moderation - to keep the climate right for your friendly bacteria and creatures; air is necessary to ensure you have aerobic digestion, not anaerobic; soil is a useful starter as it introduces the useful bacteria. Of itself, it is not going to add a lot to your compost (soil in, soil out) but it brings with it a lot of the action you need.
*INTERESTING 'FACT'": if you can tear your junk mail, it is suitable for composting. Modern inks have to be of organic origin; 'windows' on envelopes are now corn starch or similar - as can be tested by the tearing test. Love your junk mail, and compost it!