Waiting for my newest goodies....

Though I typically do landscape style photography, and of course people to support my habit, I have recently gotten much more interested in bird photography. It is challenging, and it is something I can see myself doing when I am 80 years old, and unable to be mobile as much. That being said, I have been saddened by my inability to get as close to the birds as I have seen others getting....so I dropped some cash and got a sigma 150-500mm HSO, OS Lens and hope when it arrives I am pleased. What do you guys that do birds an wildlife have in your arsenal? Any tips :)?