A plant can always be, and in fact should be, cut back to the space it can bloom properly in. Usually they are bloomed before needing to be thinned out but not always.
There are many ways train correctly ... and almost right, and good enough... to fantastic.
There is actually a lot about training to learn to do it right. But it takes almost no understanding to to it correctly.
Supper cropping is not a novice technique. You should start with something easy like tying back the major stalks.
There are pros and cons to every method.
As for how I do it it, it really depends on the grow, the strain and my goal. When I am on the hunt for a good mother it is different then when I am growing out a plant I know is female like a clone.
Do I want to veg for 35 or 55 days?
There are actually a lot of things to think about. I think the most important factor is the most overlooked. The fact that you can grow one plant per grow light if trained correctly for a few extra weeks is really awesome. Fewer pots is way less work. 2 plants is twice as much work as 1 plant WRT watering and ferts. 4 plants is twice worse than that.
But there are advantages to doing it all real fast.
If I want to grow a big fatty I will SCROG it. Nice things about a scrog include is it is forcing from one point on one side and is easy to adjust. Major Con is you can't make any mistakes. Removing the plant to flush it or do any work on the plant individually is very difficult... if possible.