Super simple blend 1:1:1 ratio
1 Part High quality compost (im using home made worm castings)
1 Part Peat or Peat substitute (im using coco coir for various reasons)
1 Part Aeration (im using perlite in this mix). 1 little note with aeration, your looking for a nice small particle around 2-5mm so a oystershell grit is also a good option if weight isnt an issue
its advisable to inoculate with a known culture of beneficials but depending on the quality of the compost input this is kinda optional in my opinion
Happy growing