I don't know of a special trick, but I know some folks have trouble with this because it came up recently. To get the k2tog you can pull down a little at the base of the stitches that you are going to work into on the left hand needle. That will open them up a bit more to help get the right needle into them.
If you hold the yarn in your right hand, just bring the yarn to the front and keep it there as you knit the next 2 together.
If you hold the yarn in your left hand (as I do), bring the yarn to the front and up to the top of the right needle and try holding it there with a handy finger (I use right index) as you knit the 2tog.
With practice it will get easier.