How you create "well-draining soil" is dependent upon the makeup of the soil currently in your garden.
Sandy soils will drain easily—perhaps too easily. In addition, sandy soils are notoriously bad at holding nutrients, requiring more fertilization. Amending the soil with organic matter will help on both counts.
Clay soils often hold too much moisture, squeezing out the oxygen between soil particles and producing a dense texture that is difficult for roots to penetrate. Compounding that problem, clay soils can crack at the surface when dry, creating fissures which expose roots to sun and arid heat. And as it dries, clay uses reverse osmosis to pull water OUT of the roots of plants in order to maintain its moisture level. Sticky and heavy when wet, hard as a rock when dry—if you have clay soil and wish to preserve your tools and sanity, amendments or raised beds are a must.
Caliche is a combination of calcium carbonate and clay. This combination forms a layer of very poorly draining white chalky alkaline clay. A caliche layer will typically occur from 6 to 12 inches below the surface soil layer. Dealing with it isn't easy—often requiring a pickax and a ferocious battle of wills. When planting deeply rooted trees and shrubs be sure to "punch through" the caliche layer to the soil below. This will greatly facilitate drainage through the hardpan.