When he joined the Avengers that pretty much what he was...a fan boy living his dream and a little too eager to please at times. At this point though he does need to be written as a seasoned pro. Walking into a room with Cap and he would be just like "Hey, Steve...what's going on?"
Another important thing is to show how skilled he has become knowing how to handle himself in hand to hand, the ability to size up whatever situation he is in, and be able to think tactically and strategically. Maybe even have earned a pilots license due to his experience not just with the Avengers but his time with Air Force veteran Ben Grimm.
Basically look at some one like Cyclops and mirror Vance skills wise.