A few things I've learned:
1) Be busy. Unless its a really posh restaurant that pays people to stand around in case someone drops a fork (which it doesn't sound like it is), you're not being paid to stand around. There's always something to do. Always. I used to work in a tiny restaurant that had 15 tables and was often completely empty. Even when it was completely empty, there was something to do. If all else fails, clean. There's always something that needs cleaning or refilling.
2) If you mess up, tell someone. Look at the bigger picture, the fact you wrote down beef when you should have written chicken isn't going to ruin anyone's life. Sure the chef will be pissed off if you go and change it. But the alternative is bringing a customer the wrong meal and then getting in even more of a hole. everyone makes mistakes. If you make a mistake, don't try and cover it up, its really not that big of a deal. Tell someone and sort it out.
3) Don't take **** personally. Chefs are generally tossers. They will bitch and moan and tell you to get out of the way and you're crap, and you're doing it wrong. That's just how it goes. Don't take what they say as a criticism of you personally. Its likely that they've ballsed something up themselves and want to get mad at someone. Kitchens can get pretty heated (verbally, not just the temperature) but it'll all be forgotten within about 2 minutes. That's one of the good things about kitchens. Everyone screams at each other and then leave as friends (generally). Its not personal, don't get upset.
4) Customers are idiots, but they are paying way over the odds for the food on their plate because they want and experience. and part of that experience is they want to be correct. Ok so they did book the table for six and then turn up with seven people. If they insist they booked for seven, then they did (even though you know they didn't). Get another chair and let them believe they were right all along. Its not worth the argument.
5) Carry what you are comfortable with. You can easily learn to carry a silly amount of plates at once, but if you are at risk of pouring the soup in someone's lap in doing so I'm sure they'd be happy to wait another few seconds for you to make a return journey. I can hold four plates easily enough (I can balance, pick up and put down five empty ones, but am not strong enough once they are full!). But, if I'm carrying four plates, its going to take me about 15 minutes to tiptoe over to their table and carefully put each one down without spilling anything. Or I could carry two, go back to the kitchen and carry another two in a few seconds. So what's the point in carrying more? I always carry two (unless its a starter or sideplate of something, those are much easier).
The best waiter I ever met was a chap who worked in a hotel restaurant with me. I once was carrying food to a table with him. There were 5 soups, I had 2 and he had 3. In the course of putting one of the soups down, someone knocked him and he spilled the whole bowl of soup on his arm. The man apologised, the water said "That's ok, Sir, don't worry about it. I'll just go and get you another bowl". He walked through the kitchen, out the back and then screamed and pulled his shirt up and the whole of his lower arm was covered in blisters. I've never seen anything like it, his arm was burned so badly. And yet when the man knocked him he didn't flinch, he stayed perfectly polite and waited until he was "behind the scenes" to go crazy.
That's a bit of an extreme example, but what it kind of illustrates is that you are part of the cast. Once you enter the restaurant you are on the stage, you are all acting. What goes on behind the scenes stays behind the scenes. If the kitchen is burning down, the restaurant should stay calm (until the fire brigade come or they evacuate the place! Haha) But in the restaurant, put your face on and smile. If you're having a bad day, that should stay behind the scenes.