Be humble. Be kind. Remember you're never as senior as you think you are. Opposing opinions are not wrong. Remember to have fun, because building things is awesome. Tomorrow is an opportunity to be better.
I wouldn't necessarily say that opposing opinions aren't wrong. Sometimes they are, and a lot of the time it's because of some form of institutional inertia. In general though, you'll have great ideas, people will politely tell you to fuck off, and you have to be able to get over it quickly or you'll make yourself hate your job.
