Some may consider this as an obvious and uniformative post but it is one of the best ways hands down to catching more fish! This will catch you more fish than simply saying troll 2 knots or use a longer leader ect. Those who use it likely know its importance and those who dont...start.
Next to actually fishing it seems that "talking fishing" is a fishermans favourite thing to do. I have learned not to be shy when it comes to talking to fisherman on the water or docks (saltwater not fresh

). There is no better way to get up to date info on where,what and when than the local guides/fisherman. Go down to a marina/boatlaunch, walk around, check out rigs and talk to anyone who looks "salty". You will find alot more local info doing this than you will checking out any forums or heading out and fishing "uninformed".
Over the years through this i have a group of around 10 friends who fish nearly daily in the summer and we rely on eachother for up to date info before we go out. The night before i head out i make my rounds of calls and by the morning i normally have a great idea of where, what and when the fish are biting on. No matter how experienced and how much your fishing you cant gain this much info alone.
This shouldnt define the way you fish as often you do need to explore and experiment on your own but it will help put more fish in the boat!