Take real good care of the dog you already have and be responsible.
If you already have a dog that is wild, (as in out of control) then you most likely aren't fit to raise another dog. While puppies are cute, they are not toys. They are living animals with needs and you need to look after their best interests. If you can prove to your parents and your current dog that you are responsible and able to care for and spend a lot of time with your animals then they may reconsider.
give reasons on why you should get anothertell them how responsible you'll become up with ideas on how to handle the dog money wiseand show how responsible you are with the first dog you have
Find out why they won't let you have the dog, and then fix whatever you can to be able to have it. Like if it is your parents, prove to them that you can take care of it, and show them that you are responsible enough for that.
You should take a picture with you and the dog if you can! Or you could bring friends over and show them that you are buying stuff for the soon to be dog!
If i were you i would ask if i could get a dog if they say no then do a lemonade stand or sell things on craigs list and try to get some money then walk up to your parents and say i have the money ill pay for it!!!. oh and i would find a dog that wont cost alot of money. try craigslist and ebay.
if you want to buy a dog you need to start doing jobs for your parents or neighbors i do that. or if your wanting to prove to your parents that you are responsible i wold walk dogs or dog sit for someone THAT YOU KNOW. that is the most important thing!
Ask for a horse or elephant or something then when they say no to that, ask for another dog then they'll be glad to get you a dog instead of a horse or elephant or whatever!! :) From Me :)
Move the dog
By doing jobs around the house and asking nicely while providing a reason why you would like another dog
You should be older 8 years old but it has to be ok with your parents or who ever you live with is ok getting a dog.
clean your room put everything where youll find it and do your chores (if you have any) and just hope and wait
If your mom doesn't know whether or not you should get a dog, it is probably because she doesn't know if she can trust you or not. When I wanted to get my dog I had to prove to my mom that I was responsible enough to handle it. Hope this helps!