If you stick with stock voltages then it shouldn't reduce the life of the ram with such a small overclcok.
It's always good to use temperature monitoring programs when you overclock. You should understand what "safe" temperatures are for your system components.
Whatever you do, don't up the voltage on your ram. Changing clock speed is probably fine, but will very likely make your system reboot and cause instability. You can "overclock" by both changing CAS timings and the frequency. You might search for the guides on the internet.