Once you've grown accustomed to the router, the tool will fit naturally into your grasp. Initially, however, it may feel foreign indeed, quite unlike other tools you know and like. Wear ear protection, as well as safety glasses, since the tool tends to produce a considerable amount of noise.
Two-Hand the Tool. Use both hands when running your router, that's the first rule. Which means that you must fix your workpiece securely onto a bench or other surface.
Hold the router firmly until the motor reaches full speed. Keep the bit clear of the work-piece, as the rotation of the motor will make it want to spin out of your grip if it's in contact with wood at startup.
Use the Rotation. When you look down at the top of the router, the motor turns in a clockwise direction. Use that to your advantage, moving from left to right on the edge facing you so that the rotation of the bit will draw the router into the cut. For routing the perimeter of a piece, work in a counterclockwise direction; when working on an interior cut, drive the machine clockwise.
Listen to the Tool. The motor will “talk” as you use the tool. With some practice, you'll learn to recognize the sound of a groan (when you are pushing too hard, it means don't cut so much at a time) and the lonely squeal (when the blade spins at full speed with nothing to cut). There's a set of happier sounds in between, when the router is cutting its way at a measured, even pace.
Start with Straight Edge. When relying upon the pilot tip on a bit to guide your cut, make sure the workpiece has a straight or regular edge. If it doesn't, the shaped surface your router will make will reproduce any unevenness.
If you're cutting dadoes or grooves, a straight piece of scrap stock can be clamped to act as a guide.
Cutting End Grain. When shaping only the ends of a workpiece, start at either edge and meet in the middle. If you're doing all four sides of the piece, do the sides first and then the end grain. This will avoid tearing out stock at the corners.
Router Jigs, Guides, and Templates. The router is a remarkably versatile tool, and is made even more so when jigs or guides are used. Some are as simple as a piece of scrap clamped to the workpiece as a guideboard; commercially available jigs enable the router to make quick work of dovetails.
Follower guides (a bushing mounted on the base, through which the bit passes) are also very useful in many applications, to protect the templates while still guiding the cut precisely.