Create incentives One of the chief problems with siblings sitting for siblings is the fact that there's no incentive for them to do it right. With a professional babysitter, there's a clear contract:
They sit well + you pay them = everyone's happy.
With siblings, it's not so simple. If there's no clear incentive for them to do a good job, you might end up with the kids parked in a playpen for hours while their older sibling plays with the Sega. The good news is, however, that incentives for your kids need not be monetary. If you're open to a raise in allowance for sitting jobs, that's a clear and easy inventive path to follow, but if you're not, consider trying to trade. Good examples of barter incentives might be the use of the family car, exemption from family chores or extra TV time. Teaching kids that there is a reward for a job well done will also pay back later in life.
Know your tweens
It can be hard to ease a 12-year-old or new teenager into the transition from kid to grown-up. They might act like an adult most of the time but revert when you least expect it. Bear this fact in mind, and make sure not to expect that they will be professional at all times during a job. Watch your new adult to see what triggers his or her occasional lapses back into "kid mode," and try to remove anything that stimulates this change. It might be goading from a younger sibling, the taking of clothes or toys or hogging the bathroom. If any stimuli that prompt this change can be removed, it's a good idea to omit them.