Generally an arm, or cove, with a major creek entering it will be more productive than just a large bay. Think about the upper ends of the lake. During floods big trees will wash down and hang up on ridges and turns or the bottom in shallow water. Here is a sure location for you to find fishable structure on strange major lakes. Because most of our mega-lakes are river fed they will have more logs and trees washed down than smaller creek fed lakes.
Every lake has some local lure color or bait that is more productive than others when used on it.
If you feel like a new lure will help catch fish on a lake by all means buy one. Just remember tackle dealers are there to sell lures, so use common sense when buying. No matter what locals may say, if you don't believe a bait will work you will not fish it to its full potential. Confidence is a major player in solving the puzzle of any lake of any size. If you have confidence in a certain lure you will keep it in the water instead of on the deck.