Try to sneak into an irreplaceable position, where you can ask for whatever salary you want. Tech is full of these opportunities. As a junior, you are often given unsexy, boring stuff that nobody wants to handle. That's a good place to get lots of leverage.
Be friends with everyone, especially other departments further away. Social ties are a mesh, and the more mutual friends you have with, say, a boss, the higher everyone's opinion of you. If three of someone's friends like you, chances are they'll think well of you too.
Learn to listen well. Listening is something that needs to be learned. This is the easiest way to make friends. It also unlocks most leverage. You'll learn surprising things. Like a subordinate might care more about being in the same department as a cute intern rather than being promoted and getting more pay.
My core rule when dealing with politics is just to know yourself and know your counterparts. Everything else is easy once you do.