The best way to keep a plant short and bushy is with a combination of LST (Low Stress Training) and topping.
Here is a walk through on a LST:
Step one. Start them with a gentle bend to get things start.
step two. Now that the plants top is growing into a bend time to step it up a bit. here I added another tie to the base of the plant pulling in the opposite direction og the bend. I have also increased the tops bend.
then as time goes on I retie the top to bring it closer and closer to a horizontal line.
Here is the end results:
For help with topping I suggest you read over Rose mans guide to topping and fimming Topping