How to avoid collapse of yeast-raised dough?
There are three major things that will cause collapsed yeast raised breads:


Underdeveloped gluten (possibly from insufficient kneading), which doesn't create enough of the gluten network to hold the gas from the yeast, especially during oven spring.  This may be exacerbated by using low-protein flours, which do not generate as much gluten as high-protein flours (called strong flours in Europe).  This tends not to manifest as a collapse, so much, as a failure to rise.
Considerable overkneading, to the point where the gluten network begins to break down, and cannot hold the gas (this is quite unlikely, unless machine kneaded)
Over-proofing (allowing to rise or ferment too long), which creates more gas than the gluten cells can hold, leading to their rupture and collapse when the heat of the oven causes expansion and oven spring.  This leads to collapse of the loaf.


Without more information, it is difficult to tell which of these you are experiencing.