THIS IS JUST MY HUMBLE OPINION.
The most important thing you can do is select the best seed, clone or the strain that you are starting with. Genetics is very important. You wnat a bushy Indica.
I've learned from a few years experience to toss those runts and sickly little plants. If I see I have a runt, I just pull it up and start over. I've learned to really examine the plant and see if it has lots of stalks (like in the pic at my signature) or is it just going to be like a single stalk of corn with no or FEW major branches from the bottom.
I think others will talk about nutrients, air, water, soil, nitrogen, carbon dioxide, dry ice, etc, but I wish I knew a real good way to increase buds. Of course,t eh bigger the plant, the mroe buds. i've done alot of experiments with STRETCHING and I try for BIG PLANTS. STRETCHING helps me get a big plant. I raie my lights 12 to 16 inches TO FAR away, for one day only, then move them back close as I can the next day. The plant reaches for the light and grows faster toward it. That makes more "node room" which gives me more buds. I also pinch off the tops at 2 and 3 weeks. a double grows back!
Good Luck, bro
Peace!