How to stop your mom from getting mad... It's the age old question! I can't say I ever figured out the answer when I was kid, and to some extent, I'm glad about that. It's a rite of passage that everyone seems to go through, and you learn from the times that she does get mad what not to do in the future.
Tell the truth. I remember sneaking around behind my mom's back, and going to places that I shouldn't, and in hindsight that wasn't a great idea. Your parents worry because they love you, and want you to be safe, so don't add to this worry by creating situations where they don't know where you are or who you're with.
Tidy up! It seems like the last thing you want to do when you're a kid, but I guarantee if you keep your room clean and on top of your chores, your mom will be your best friend!
Respect her decision. If she doesn't let you do something you want to do, suck it up and accept it. It's annoying, yes, but if you show maturity in accepting her decision, maybe in a few months time if you ask her again she'll be more open to it.
Remember- all mom's are different, only you really knows what makes yours tick!
Here are some more tips about staying in your mom's good books: