If I would start new soil, I would take a few things into account:
These things work together and makes the soil balanced. Nature does it out of the box, so trying to mimic nature is a good start.
Moist (water) is used to transport nutrients deeper into the soil. It also transports micro-organisms further around.
Oxygen keeps everything alive. The soil needs oxygen too. It's for the micro-organisms to multiply and to 'burn'. No processing is going on without the oxygen. Cell division thrives on oxygen. Micro-organisms have cells too, they want to spread!
So, with that being said... What to choose? In the answer above Mel's Mix is mentioned. Very good choice! There are other comparible mixes or alternative ingredients available. Look around for a mix of dirt, clay and compost. The dirt can be somewhat coarse for the oxygen. Clay is good for the moist. The compost is for starting up with the micro-organisms.
I suggest to watch "Back to Eden" about topping off the soil with wood chips. Organic, clean, mixed wood chips. This is very natural coverage of the soil. It will keep it moist when needed and give of water in times of hot weather. It will also soak up excessive water. Further it will be coarse enough to let even more excessive water seep through to the deeper soil.
You can add wood chips later too. Or add additional every (other) year, so it will build up natural layered structure. This is awesome for healthy soil. After a while you don't have to do anything anymore than just let nature do the work. Not tilling, no chemicals, no plowing, no fertilizers. The "do-nothing" method like Masanobu Fukuoka calls it.
I also suggest to read the book "Teaming with microbes". This will give you an idea about what lives in the soil, how to support it and how it enhances your plants and trees.
For advanced soil, I would look into the mycelium/mycorrhiza and things like bokashi. This way your plants will grow strong and healthy!