The best way to do this is to trim is slowly over time to encourage grown in the direction you want. Trim it about a 1/2 inch at a time and let it grow for a week or two in between.
Trim at a "joint" a place where a branch joins a main trunk. Don't trim in the middle of a stem because it will leave an ugly "stump". You can re-root the trimmings in sand for new plants if you wish.
