Simple is to turn off lights & power when not in use!
A step further: Separate garbage from recyclables and recycle as much as possible. You can recycle bottles and get money back. Involve the whole family by getting everyone to help and then guess on how much money you'll get back, the closes guess wins the pot!
Buy in bulk when possible. Less packaging and lower prices (Shampoos for example, buy in bulk and then pour into reusable containers.)
Reuse products when you can. Reusable water containers vs disposable water bottles. Refill ink cartridges for your printer.