The oldest advice for bird photographers is, "Put your back to the sun."
Shoot burst mode with flying birds. If you hang out with a group of serious bird photographers on a walking shoot, it can sound like a machine shop with all the shutters firing continuously.
With long lenses it takes some skill to follow a flying bird. Practice. Dogs playing in a park are a good subject for that.
Hand holding long lenses is possible if you follow good technique. It's worth googling the subject.
A gimbal mount greatly eases tracking with a tripod. They're heavy and expensive but very smooth and fast.
If you're shooting through lots of branches, you'll often have to manually focus. Even spot focusing can get confused in heavy brush. Practice.
Learn to adjust EV by touch, and pay attention to your setting. Being able to guestimate exposure compensation for your situation will increase the number of keepers. You'll have to adjust higher for flying birds and often lower for dark backgrounds like conifers. Even spot metering can get confused.
Cultivate patience. Finches, sparrows, chickadees, gulls, pigeons and crows easily get used to people. Once you get past that low hanging fruit, quiet and patience are essential.
michael mckee
My Port Townsend – A City in Photographs – 365