How to make flashing lights in Minecraft with repeaters?

With Redstone, there isn't really a right or wrong way to do anything. Here is one simple technique you can use to create flashing lights.

In this image, the part of the circuit at the bottom is known as a clock. It switches the Redstone Torch connected to the block from the on and off position. When the torch is off, no power is sent to the repeaters. This allows the torch to turn on. Then, the "on signal" travels through the repeaters and turns off the torch. This pattern repeats infinitely.

The signal is then sent to the repeaters in the hole I made. When power is sent through the repeaters, the block in front of them becomes "powered". This turns off the Redstone Torches mounted on each of those blocks, and in turn, alternates the Redstone Torches on the surface on and off.

Like this:

B = a block of whatever
W = redstone wire on the ground
T = A redstone torch
R = repeater

TB  <- torch connected to the side of the block
RW
WW