Heh, I used this tactic for getting neopoints on neopets but I'm sure it works with real money too. Actualy, this is my plan to save up for an AIBO.
• First set some goals. Maybe you want to get $10 or $20 a month saved. You can do more or you can do less. Expirement for a month and see how well that works. Ajust the goal amount if needed.
• Along with the total money goal, set a percentage of the money that will go into your laptop 'fund' from each amount of money you recieve. So, if you say you will set aside 20% and you get 10 dollars for watching a sibling, you would but 2 dollars into your fund. Put at least that much into your fund and if you can, more. But at least what you set up. I would start with 30%-50% at first and then change if needed.
• Keep your money organized. I personaly have a little pencil case that I put my loose money in. Every once in a while I deposit some [if not all] of the money into my bank account. Ask your mom to help you set up an account if you do not already have one and deposit your money every [couple] month if you can.
I need to follow my own advice in this case if I want to get my AIBO. xD