I use a peat based mix and may add perlite, or bark chips, or coir 'chunks' which have fiber in the bag too. That depends on the plant.
I am not very 'professional' about this. I primarily use a commercial peat based potting mix- currently a Lambert mix sold in a bale.
I have a big assortment of plants. I've seen a huge range of plants do well in fresh quality brand, commercial mix.
