How to find the gib ones!

I can consistently go to many lakes and find and catch crappie of decent size. The big ones I can find get up to 3/4 to 1lb, so not really huge but I can find the 1/2 - 3/4 lbs in large quantities. This gives me the notion that I have at least some understanding of how to catch these fish.

The question i need help with is how do I move from that into finding the large ones. What type of environment do the big ones like, what do I start looking for?

I am sure that this isn't the first time it has been asked but I haven't found the answers yet so if this is read the forum stupid question I apologize....just point me to the correct forum and I'll will, but any hints would be appreciated!

I have found the fish seem to be grouped together by size. One brush pile or dock my be covered in 9 inch fish. The next one down the fish may average 12 inches.