The one thing you should add to every soil type is well-rotted compost. This gets soil microorganisms going, which can make nutrients in your soil more available. Be careful as the USDA does NOT regulate labels on garden center products the way it does for food. The terms natural and organic do not guarantee non-toxic. I only know of these groups that certify products: Organic Materials Review Institute (OMRI), the California Department of Food and Agriculture (CDFA), and the Washington State Department of Agriculture (WSDA), though there may be others. If you only intend to grow ornamentals, it doesn't matter as much what is in a soil additive. However, municipal composting often includes sewage sludge which can contain anything from flame retardants to pharmaceuticals.

Dig into your soil one spade deep and break it up. This is often easier in heavier soils when the soil has moderate moisture. If your soil is hard to dig in try watering it two days before turning it. The more clay in your soil the more important it is to get this right. Too dry makes the soil hard and clod-forming. Too wet and the soil sticks to whatever tool you use to turn it, and clods can also form. Add 2 to 4 inches of compost over the turned soil and turn it in again continuing to break up lumps of soil/compost. After turning in the compost, use a garden rake to break up smaller soil lumps and rake the bed smooth. That's it; you're ready to plant.

Remember that if a plant will grow to 4 feet wide it needs a 4 or even 5 foot wide bed. New plants are going to be small. Don't crowd shrubs and perennials; fill in around them with annuals for the first few years. After planting, place a fine mulch over bare earth, but don't mulch up to the stems of new plants.

Don't know where you are, but it's too hot in most of the U.S. to be planting now.

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