Too many to C&C really, but some general advice....
1) Overall, Watch your exposures and your white balance. Try spot metering the bird if you have to.
2)Try to keep the sun at your back. or atleast the "3oclock-9oclock" positions.
3)Try to shoot early. You will notice in most case, the birds try to get up into the trees and warm up in the sunlight. This not only gets them to sit still a bit, but also will light them with direct golden hour sunlight.
4)If you are going to shoot birds quite often, ditch the 300 f/4 and TC for a 400mm f/5.6. If you are living at f/5.6 with a TC on it anyway, what benefit are you getting? (you're just destroying your IQ ). IS is not that useful in bird shooting.
5) practice getting closer and closer to the birds each time. You will get used to moving very slowly and deliberately. I noticed after a couple years of birding, during a dimly lit morning, I pulled out the 70-200 f/2.8 thinking "what the heck, might as well give it a whirl." Not expecting much. What I found was, I had gotten much better at approaching birds and suddenly a 70-200 was as good as a 300mm used to be.
6) be very very patient.