Hm, I'd have to suggest the opposite. I can't see focusing as an effective way of falling asleep since that's the one thing that seems to keep one awake.

Think about how you usually fall asleep - random thoughts fill your head and you drift off. Those thoughts then turn into hypnagogia and so on.

So, if you can't fall asleep, don't think about falling asleep. Just lie relaxed with eyes closed, resting, and thinking of anything. Don't do it willfully, just allow your thoughts to flow freely, about anything and everything, as usual.

I usually don't fall asleep until an hour after I get in bed. So, perhaps this is a subjective point of view but I'm speaking from experience so hopefully this advice might be of use.