In all likelihood you already know of the vast majority of these. I'm not the first person to put some variation of these on the Internet. Many of these are just common sense. Less energy used = Less energy costs. If you check a money saving or an environmental concerns book or website they will say much the same thing as this.
Use or replace existing items with more energy efficient versions.
Purchase fluorescent or even better LED light bulbs.
Use rechargeable batteries instead of disposable ones.
Use a laptop instead of a desktop (uses less energy).
Use solar powered objects if possible (Solar powered battery chargers for instance).
Purchase Energy Star appliances.
Fan instead of air conditioner.
Use a microwave or toaster oven to reheat or cook since it uses less energy than conventional ovens do (if possible solar cooker since is most energy efficient).
Use a battery powered or better yet a water powered clock instead of a plug in clock since plug-in clocks use a lot more energy than they need to (10-100 times as much).
In general if there is a battery operated version of something you use that plugs in switch to that since they generally are more energy efficient (if your using rechargeable batteries).
Toilet and shower head with low flow versions.
Front loading washing machine
Tankless Water Heaters.
Sponges and rags instead of paper towels.
Insulate/winterize your house as much as possible (plastic over windows, blanket in front of door crack, etc.).
Turn off the lights when your not using them (This is fairly obvious).
Turn off water when not using it. In other words do not leave the water running when brushing or shavings.
Water your plants early in the morning or in the evening. Avoid watering mid day because more water will be lost to evaporation.
Do not leave appliances on standby. Appliances still use energy when left in standby mode it is much better to turn the appliance off. Even better unplug them or if on a plug strip switch the plug strip off.
Wrap your water heater in an insulation blanket. This will make it so your water heater doesn't have to run as often since the water will stay hot longer.
Insulate your water pipes.
Put on a sweater instead of turning up the heat.
Air dry items if you can - clothes instead of using the dryer, dishes don't use dry setting on dish washer.
Fill up washing machines and dish washers before using them. If you do use them when only half full or something be sure to set it at half load (or equivalent setting).
Cover pots when cooking since it cooks faster and conserves more heat. Also add a little salt to water so that the water boils at a hotter temperature causing items in the water to cook faster.
Move fridge and freezers as far from heat sources (heater vents and ovens) as possible because they will have to work harder to keep cold.
Sweep your yard with a broom or rake instead of using a hose or air blower.
Put a piece of aluminum foil under your ironing board cover to reflect the heat and make ironing faster.
Keep water in refrigerator for drinking instead of running water until the water cools
Use cold water washing since you uses less energy.
Lower your water heater temperature to around 120°F unless you really need a higher temperature.
Take more showers than baths. Bathing takes more water than showers.
Close your curtains at dusk to stop heat escaping through the windows.
Turn off stove and oven a few minutes before time is up. Residual heat will finish the job.
Bake foods together if possible (ex. Bake the cookies with dinner instead of separately).
Turn off decorative outdoor gas lamps - these are just wasteful.
Do maintenance on items – Things in good condition are more efficient and last longer.
Repair leaky plumbing (faucets, toilets, pipes, etc.) promptly. Your just wasting water otherwise.
Clean or replace filters on your furnace, air conditioner, air purifiers, vacuums, dryer, etc. Do this regularly since dirty ones don't work as well and use more energy (some like dryer after every use).
Clean (vacuum or brush off) the condenser coils on the back of your refrigerator/dehumidifier at least twice a year.