According to Florida landscaper, Rachel DeToro, creating great soil is like making good lasagna. It’s all about layers of organic material on top of other organic material.
Start with mushroom compost on the bottom, followed by a layer of pine bark mulch (finely grounded). For the next layer, use seaweed (rinsed to remove salt) or leaves or clippings if seaweed isn’t available. Finally, add another layer of compost. To protect the soil and retain moisture, top the bed off with a layer of pine straw or leaf mulch.