ive modified my "favorite" soil mx somewhat..
i like richards mix..
mine is my own compost(straw,shredded leaves,rabbit manure)
perlite,coco coir,and ive added shredded composted orchid bark now..
i use sand in the outside gardens.. to pots i dont..they are to heavy..
oh my aching back..LOL
reason im adding shredded bark now is for even more drainage..
i have good drainage in my outdoor gardens.. just thinking the
less the roots sit in water and drains away.. the better..
i also try to keep the pH of my soil pretty much neutral.. not on acid side..
we have pretty alkaline soil here in utah..so i havent had to worry to much
on that..using peat ..sometimes instead of coco coir...
great to see what others are using.. thanks