Big Gav posted a reminder on how low-tech gear such as scythes can make a small dent in our energy usage.
As I tend to use both a scythe for weeds and a hand push lawn mower for grass, I thought I would toss out a few pointers.
Get a big sharpening stone to keep the blade sharp. Stroke in one direction only, away from your body to make it less likely to accidentally slice your hand in two. Alternate sides of the blade with each stroke. Make a lot of noise when you grind away, so the next-door-neighbors get scared.
For hand push mowers, learn the technique of removing jammed sticks without having to reach down with your hands. Essentially you instead stop pushing briefly and use the bottom of your shoe1 to spin the mower rotor backwards. This effectively dislodges the junk that gets stuck during the forward motion. Trust me it works, and saves lots of time if you have a woody lot. Of course, the alternative remains to just grow ground cover and you won't have to do any of this.
As for leaf blowers, wait for a windy day :)
1Feet also work for snow shoveling. I have perfected a really silly technique where I use my legs to methodically catapult snow off the shovel as I clear sidewalks and driveways. Good way for the footballer's in the neighborhood to keep in shape during the off-season.