Topping is a simple technique of cutting the tip or top of a branch off using sharp scissors. It doesn't matter if it's the main(stem) top or the tip of a side shoot, the resulting effect will be the same. Instead of one top or tip resulting in a single bud, the treated shoot splits and produces 2 or more tips. Never top an unhealthy plant. It is debatable whether or not this practice will actually increase or decrease the size of buds or overall yield. A healthy plant generally thrives under careful stressing and physical manipulation. This is not something you want to overdue, start slowly and increase the frequency and intensity of your pruning practices over consecutive crop cycles. Gain some experience so you can recognize when you have overdone it.