
I used to do dog walking and dog sitting when I was at college, it all happened through word of mouth, people asked me or heard about me from others because I was doing a college course on animal care, worked in a pet shop and had 3 dogs of my own - two of which were large. To be honest you might not have a lot of luck walking peoples dogs because of your age and lack of experience, I dont mean to be patronizing when I say this but it does take a lot of trust to let someone take your dog out, but obviously it depends on the dogs owner - and the dog ;) The other thing these days is insurance, if you are going to advertise and charge people they will expect you to have some sort of insurance if you dont and something goes wrong you could be sued. And again I dont mean to be patronising about your age but you have to be careful these days about whose door you are knocking on, there are too many dodgy people about. I personally think your best bet would be to contact a rescue centre and see if you can help out in any way, although they may have an age limit. Sorry I havent been much help, but good luck :)