the only plants i tip are my mothers,once ive got a clone im keeping for a mother to about 6-8 inches tall i take the centre out of the end of each branch,then i do this afew more times to get the plant really bushy so i can score allot of clones off it in one hit,usually between 30-40 .tipping a plant wont usually increase my yield with the strains i grow if im only growing small-average sized plants,you dont get those huge colas ,but if you want to grow a monster ive managed to get over 8oz off big plants,from memory the best ive managed off a plant that was tipped alot while vegging was 12oz oz dry bud,but they take way too long to grow imo,better off not tipping and growing a bunch of 2oz girls