Most native plants will generally be satisfied whatever your soil. Adding nutrients Earthworms are important and affordable soil builders. Eating and excreting their way deep underground and then back to the surface, their soil processing increases nutrients available to your plants and tends to balance the soil pH. Unlike chemical fertilizer, earthworm castings will not burn plant roots. Earthworms and their co-workers consume and process leaf litter and other organic materials. The more humus in your soil, the more earthworms.
Most organic gardeners have a good sense of humus.
To add humus to your lawn, mow rather than rake leaves. Persistent raking slowly removes this source of humus and thus starves the earthworms and their cohorts. If you mow your own lawn or have a lawn mowing service, leave the clippings where they fall. This will save time and improve your lawn. This is especially true if you fertilize your lawn.