potting soil

I have a 71 year old Juniper (shimpaku) that was handed down to me. It is time for a repot, but I have no idea what type of soil mix to use. I'd like to mix my own but need help from everyone on the exact ingredients and amounts to use unless you can recommend a reputable brand of premixed soil...

Last spring I bought three pitch pine saplings and put them into the ground, I didn't do any root work on them since the were a bit weak, but they got much stronger over the last year. But now I noticed that one of them has some terrible surface roots going up and down and stuff and it had...