I've answered this question a few times this week on various threads.
Without knowing what type of system you are running, plant numbers, light size, strain etc. it is tough to give a desicive answer.
I can tell you a few things though. Try to leave as many leaves as possible. Try bending them or manipulating them out of the way if possible. Also you can cut SOME of the leaf off, leaving about 60% in tact so the leaf can still function. You need these leaves for a number of reasons. They store nutrients, and create sugars. They are essential for the plant to photosynthesize.
I am also going to be starting a new thread on plant numbers and canopy management, so be sure to check for that.
One thing that many people overlook, and is very important to consider is YOUR PLANT AND ITS STRUCTURE AND GROWTH PATTERN. A short stout indica and a tall lengthy sativa will need different amounts of space both vertically and width wise to grow.
When growing in a SOG (or even single plants for that matter), it is important to consider your plant structure. This is important because (like your said), improper canopy management leads to shaded budsites. Shaded budsites are a shame because 1. It was a waste of time growing these sites, all to have them shaded or cut off. 2. because the plant wastes energy focusing on these shaded sites, instead of on the larger top nugs. 3. because you have to do intense pruning which sometimes leads to stress or diminished yields or quality.
For all these reasons it is important to find the best method for growing your plant. Sativas can be packed together with the pots touching and the light can still penetrate through because of the open, lanky structure of the plant.
An Indica on the other hand (which if i had to guess, would be what your growing) can sometimes be more tricky. I grew really short stout indicas with huge fan leaves. The leaves basically shaded almost the entire plant and left me with the same problem as you. I would have 4' plants with the bottom 2 feet cut off. Seems stupid to waste all that time just to cut it off right?
Sooo... what did i do? For large plant setups i would top early and LST the plant into a little bonzai tree. The most successful method though was quadrupling my plant numbers and going from 3 gallon pots to 6'' squares. I would flower much smaller 9''-11'' plants and get MUCH better results. Each plant would yield SLIGHTLY less than the 4' plants, but i got all primo large colas that were much higher quality than all those little popcorn "bagfiller" buds i used to get off the bottoms of my 4'ers. I found that my plants could use there energy on those fewer brances, and although my plants were much smaller, my bags were filled with MUCH bigger HIGHER QUALITY buds.
Sometimes i get a little long winded and go crazy, but i hope this helps you a little bit.
Oh, and to answer your question. I would first try manipulating the leaves out of the way. Then secondly, cut in half the leaves that are still blocking you up. And finally cut off any budsites that still are not getting good light.
Good luck, and good growing