Sure, fishing the edge makes for a good shot at a wally. But, if you are gonna fish open water, (past the edge), start thinking currents and convergence. I rely on reading current more than anything else. Combine that with the chloro count and temp breaks. Also, it doesn't hurt to look at the altimetery. Try to get between "rising" and "sinking" areas. Always be on the lookout for debris and bait. Not many objects are too small to hold fish. Don't think that open water is less productive. It's not. You want a shot at the big girl? You oughta go there.