I used to belong to that bonsai club, they are very nice people, you will enjoy it. The soil is pretty easy, just make sure that it is well drained. The only different is soil type for different PH requirement for different type of plants. Azelea like Acidic soil so you want to add peat moss, fir bark, and perlite. Pine and junipers like coarse well drain soil so I use pumice, small fir bark, and some top soil, with a little sand. As for trimming their is a trimming technique for each plant type and a schedule, and then their is a schedule for fertilizing ... once you get all that then you are fine ... lol