See the Right and Left Lifted increases being worked this video or scroll down further for photo tutorials.
LI or RLI:
With your right needle lift the right leg of the stitch below the left needle.
Pop it onto the left needle and knit it.
Remember though that the existing stitch on the left needle stays there it should not be dropped off the needle.
LIB or LLI:
To keep this increase in the same place you will work it on the other side of the stitch. This means that you are picking up a loop from the row below as you have just knit the stitch.
Pick up the left side of the stitch 2 rows below the last stitch on your right needle with your left needle.
To mount this stitch correctly we will knit into the back of the loop on the needle.
Remember again to leave the stitch on the needle (or you aren't increasing a new stitch!).
Why not give this technique a try in the following patterns: