A string trimmer, also known commonly as a weed eater or a weed whacker, has been part of lawn care for nearly 50 years. A string trimmer is essentially a gasoline-powered motor on one end, connected to a trimmer head by a long shaft. The head is filled with nylon line that spins so fast that it cuts the grass. A string trimmer has unmatched versatility around obstacles such as rocks and poles, and it makes trimming in those places a breeze.
Hold the trimmer head approximately 3 inches off the ground, and sweep it from side to side, maintaining your 3-inch height. This is the most basic trimming technique, which works best for flat areas.
Trim longer grass starting near the top of the stems and working your way downward to the bottom. If you start at the bottom, the grass can tangle the trimmer head, which will cut the engine.
To trim around sidewalks and driveways, use a roughly 30 degree head angle. These areas that abut concrete or asphalt also can be edged: Just turn the adjustable handle so that the trimmer head rests at 90 degrees to the ground, then cut along the edge of the walkway or driveway.
Trim bushes or small branches by adding accessories. There are many nylon and metal blades that can be bolted on to where the trimmer head is so that you can cut brush and even small branches. Of course, the larger the engine size of your trimmer, the easier it will handle a heavier metal blade.