#1 tip: Start SUPER simple. Make an asteroids game. Make Pong. Or Breakout. If you get more advanced, make Pacman. Look at a lot of the old atari games and create them, but add your own art and design one or two variations to the rule set. At the best, this is what you should expect to be able to make straight out of school, and its a lot harder than it sounds.
#2 tip: Never quit, never give up. You'll get frustrated. You'll feel like you suck and you'll never be able to do it. Acknowledge that feeling, but keep working at it. When I first started programming C++ in high school, I got a low C in my course. I felt disappointed and as if I could never get it. I kept trying my best though, and eventually got better. I also needed to take lots of math. Math was never my strength in school. I performed poorly in pre calc 2 and took it about 4 times. I must be a slow learner. A lot of people would give up, but I didn't. As a consequence, I got four times as much practice as anyone else at pre-calc. Today, if I have to do math, I jump right in with excitement. I love it and I'm thirsty for more techniques and appreciate the beauty which hides beneath it. Perserverance is one of the secrets to success you must have. If you want to be a game developer, you have to make a life long commitment to do whatever it takes, no matter how long it takes.
#3: you'll get lots of rejection early in your career. Deal with it. We all get it at first. Don't give up. Keep working.
#4: Bring something valuable to the table, in terms of a skill which directly contributes to the production of a game. Do you do programming? 3D modelling? Animation and rigging? textures? website design and marketing? finance? project management? game design? How do you help push the game out the door? Do NOT be an "idea guy". Fuck that guy, he's utterly worthless.
#5: Manage expectations and manage scope creep.
#6: Keep the morale of your team high, because morale is the steam which pushes the production forward. To keep morale high, make lots of visible progress as fast as possible. Every day, something new should be visible. New people need that fast feedback loop (including yourself) between work done and reward received.