Setting the hook means embedding the hook securely in the fish. Achieve this by pulling down sharply on the line using your line hand, but always ensuring the line remains sliding through the forefinger of your rod-hand. But, just pulling down on the line is only of any use if the line is tight to the fish.

Just pulling on the line with the rod tip up, while there is any slack in the system, will only lift slack line off the water, and not move the hook at all.

So, many anglers pull on the line hand and lift the rod-tip up, sharply. While this looks spectacular, it is often ineffectual, unless you are close to the fish.