When I first left Uni I went to a big defence contracting company and went from graduate programmer to work area lead in 8 weeks, as much out of circumstance as capability (ie there was no one else to take the position of that work area lead). I did good work, and just as importantly (as I was told my management during my work review) by being a happy person and having good morale that brushed off onto others. No matter what stress we were under I just went around be happy and relaxed laughing and whatnot. At other jobs people have also commented on how it was nice having someone around that wasn't acting all stressed out during the crunch times.
Happy and helpful. Thats what I have always been at my jobs, and it works.