One of the biggest thing to know about maintaining soil, is keep it covered. (Except for a tiny bit where ground nesting critters can move in.) Weed fabric does NOT count as a cover. I loathe the stuff. It is useful under pathways and rock, but it has no place under mulch. I have seen normally beautiful “old” gardens soils literally turned to grey powder because weed fabric locked out moisture and nutrient cycling. I have used thick unbleached butcher paper as weed fabric when establishing a new space. It is thick, pretty darn durable, and breaks down as a high-carbon fungal food.
The second big thing to know about soil is leave it be. There is no reason to disturb soil (unless you are planting veggies- and that is debatable as well). Tilling and working the soil destroys fungal hyphae and knocks back the balance of fungal and bacterial biology. It also kills invertibrates like worms, ground beetle grubs and beneficial nematodes.
If your soil is poor and needs improving you can deep core aerate and top dress with mycorrhizae and high quality compost. This will get microorganisms down into the soil without turning the soil to powder first. You’d be surprised how quickly these organisms are moved through the soil profile by invertebrates and water. If you want to push the improvements even faster you can apply compost extract once a month to add to the soil biology but be sure you have compost, mulch or other food sources for the microorganisms.
When my family finds worms in impractical spaces we put them in a designated bed for the year. Each year we change the designated area so that worm populations improve throughout the property. It seems like a silly ritual, but its benefits are irrefutable.