As people have already advised, find the local places where birds are used to being fed and therefore come a lot closer. Try and find a branch that they often sit on before dropping onto the feeders so that the shots look natural, and practice practice practice!
You probably won't notice the little improvements in your shots, but in six months time when you compare your new images with your old ones, you'll certainally notice the improvements.
I always find getting the first shots of a species is the hardest, and I tend to keep some pretty rubbish shots, but very quickly they get deleted as better shots come along, probably because I'm learning their habits as i'm watching them. The best shots are often unplanned. earlier this week I was trying to photograph badgers and I got my best shots of Jays as they came to steal the food we had put out for the badgers and I was only using a 70-200mm lens. As for the badgers, we watched six of them for a while but being in forestry in the rain meant the light was awful and my pictures were pretty rubbish! But now I've got an excuse to keep going back to try again.
