Clearing and preparing a new plot
The simplest way to prepare a plot overgrown with weeds is to first remove any plant material above the surface using a strimmer/brushcutter, and add the material to a compost pile. This makes the next process of digging and turning the soil much easier.
Soil preparation is loosening the soil to improve drainage and aeration, and removing as many perennial weed roots as you can find. This is best done with a fork, and best results are from double digging. Double digging means loosening the soil to twice the depth of the fork or space blade. It is important to avoid mixing the clay/gravel subsoil with the good topsoil. Most descriptions of the process suggest digging a trench, removing the topsoil, digging and loosening the soil at the bottom of the trench, and then replacing the soil. Whatever practice you follow, try not to walk on any soil youve dug this compacts it again and undoes the good work you've carried out. Use a board laid on the soil to spread the weight if you need to cross an area youve dug.