1. Fish early. I can't count the number of times I'm coming back to the launch at 10:00AM with a good stringer and there's a group of kayakers just getting ready to launch. They'll ask, "man where did you get those?" I know that it really doesn't matter, because you don't catch as many fish in the middle of the day, especially during summer. Set your alarm and get out there at or before daybreak.
2. Use enough rod. Particularly on Youtube, I see guys fishing with noodles that can't control their fish once they get close to the yak. You don't need a telephone pole, but you do need enough back bone to control the fish to land him. It's comical watching some guy try to untangle a fish off of his drive, his power pole, or his anchor. The idea is to land fish, not to see how well your line can withstand contact with multiple obstructions with a fish struggling on the other end. Which brings us to #3
3. If you are going to fish around oyster reefs and other obstructions, leave the light line at home and use a good leader. Once again, the object is to catch fish, not to have to talk about the one that got away.
4. It's OK to experiment with freshwater lures in the salt, but make sure that they have hooks that can handle the salt and an extended battle with a determined fish. Most freshwater lures do not come with adequate hooks for saltwater, so change them.
5. Only use weedless hooks where you absolutely need them. Once again, this is something that I see on videos a lot. There is a reason that most upper coast anglers use a conventional jig head, and that's because you hook more fish with them than one with the point buried in the plastic. When grass is an issue, you have to use weedless set ups, but you do fail to hook some fish because of it.
I say these things to be helpful, not because I know everything, because I'm still learning after 20 years of kayak fishing. I like to see people catch fish and enjoy themselves rather than be frustrated.