1. whats the worst thing that can happen if you top a plant incorrectly? 2. can u lst a plant just tieing her down once?
I have found that the best shape for growing indoors is to have four main branches. I top, and then remove any lower branches so I'm left with the best four. They are easy to manouver where you want them. If your plants are healthy, you can cut everything green off and they will regrow (not that I'm recommending this). It's just to let you know that you can be fairly aggressive with pruning and training. Have your plants well trained before flowering, and don't do too much after the third week. you should take off most of the lower scrappy branches that won't produce nice nug. After the second week of flowering, you should be able to tell which nugs are going to do well and which aren't doing much. Remove those teeny buds sites. Your plants will produce what they will, based upon your conditions, you can have lots of smaller buds or more big buds depending on your training.
You can't really top a plant incorrectly. Just pinch off the new growth above the last fan leaves and you're good to go. You can LST with however many branches you want. I let mine get to the 8th node, then I topped it. The side branches quickly moved up top along side the 2 new tops I got from topping her. So at this point I had about 10 main tops/branches. I tied about 4 or 5 of them down just because i didn't have room in my closet to tie them all down. When you tie a branch over all your doing is letting the side stems of that branch grow upward and become its own branch. Normally, they will just continue to grow vertically with the main branch and just help form the main bud on that branch. If you tie the main branch over each side stem becomes its own cola/bud instead of just helping form one all together.
To the post above me: Yes, that could help make the plant focus on the nice buds but if you leave the bottom growth you can harvest in layers and let each layer get the light and develop. I never harvest my whole plant at one time. I take the best look buds, let the smaller ones get big, and repeat until all branches are harvested.