I own 2 of the best tripods ever made. I hardly ever use them. I teach photography including a class on wildlife. Yet to meet a student who can properly set up a tripod and also use it correctly. People think tripods are some kind of magic. Once I am on one I can do anything I want. The lens you own is indeed bang for the buck. However, it is good not great. It is very soft at 500mm and terrible at the edges. But, for birds that may not matter much. Perhaps you are doing the best you can. Yes, settings matter a whole lot. Figure out what you will be using before you start shooting, not in the midst of the battle. Of all the different subjects one could cover in the world of photography, I say that astrophotography is at the top of the challenge list. Wildlife is 2nd. I assume you know the old joke about the famous violinist who got lost walking the streets in Manhattan. He stopped someone and asked them how to get to Carnegie Hall. Practice, practice, practice. Gene