garden wire or graden stakes, if long enough. Don't forget to anchor the base of trunk to opposite side the plant is bent toward. In the picture you provide, 'to the left'
more branches is not necessarily better. you really don't need more than 3 colas per sq ft to maximize yield. some genetic variance to what is best, of course.
So, work backward from a canopy you want to fill the space and get there in a systematic way - whehther training or toppig doesn't matter. If you have a goal, you'll be more efficient with time/effort getting there.