One tip I use for collection change: Never pay for anything with change. Always use bills. Then, at the end of each day, dump your change into the bank. For example, if you buy something that costs $2.50, pay for it with bills, you'll get 2 quarters back. If later in the day you buy something else, for say, $1.40, don't fish the quarters out of your pocket, pay with bills again and you'll get another 60 cents in change. It's surprising how fast this can add up.
And yes, as Stayhomemom suggested, offer your services for anything and everything. I used to babysit, rake leaves, clean out gutters, shovel snow, cut lawns, anything that anyone would pay me for. Going to your neighbors is a good idea, too. I would gladly pay a neighborhood kid to do some work for me, usually for stuff I would do myself and wouldn't look to hire anyone to do. But, if you came to my door saying, "Would you like to hire me to shovel your walks?" I'd be happy to pay you to do so.
Also, see if you can make a deal with your Mom. Say, if you can save X number of dollars by a certain date, then you can book the cruise. That way, you'll have a schedule and can figure out how much to budget per week/month. Also, if you meet the amount, she'll see that you're serious about saving money and helping to pay for the cruise.