When you've been busy all day and evening or have weighty matters on your mind, it can take longer than you wish to fall asleep. These are things that work so reliably for me they're well-worth sharing.
If you're cold, consider placing a warm heating pad or electric lap blanket where your feet will be, either under or over the covers. Turn it on about 20 minutes before you want to get in bed.
Always start any of these by just resting with your eyes closed for a minute while your breathing slows and your body relaxes. Then take 2 or 3 deep breaths slowly in through the nose, slowly out through the mouth.
Relaxing The Tongue
This one is remarkably fast for me. When you become aware of your tongue you'll probably find it's holding some tension (along with the rest of your body). The technique is to hold your tongue in the middle of your mouth so that it is not touching anything else, including surfaces or any of your teeth. It takes some concentration and effort at first, but bear with it. When you notice your tongue is touching anything, bring it back to the touch-free position. When you wake up, you'll say, "Hmm!"
Let Your Mind Out Of The Window
The focus here is more of a progressive one in that it has stages. After the basic brief relaxation and deceleration, I try to still my mind a bit. Then I let my mind kind of rise toward the top of my head. When that seems to have been effective for a bit, I try to get just above my head and hold that for a bit. Then I drift toward the window, and up a little higher. When I'm comfortable there, I go just to the other side of the window, outside, and up a bit higher again, but virtually looking in, "seeing" myself in bed. From the other side of the window now, and when I'm at ease there, my mind does another turn towards the trees. Again drifting upwards, I head for the trees, floating gracefully through the air into the night and dreamland.
There are lots of meditation styles, and the universal goal is to quiet the mind by focusing on one thing or nothing. I find that a 2-syllable word, or mantra, works best. The first syllable happens on inhalation and the second syllable on exhalation. It is quite natural for your mind to wander, so when you notice yourself having stray thoughts, gently return to your word or mantra without judging yourself or the technique.
Note: Meditation for falling asleep is best used when you know you're really tired and body-weary but your mind is still racing. When I learned transcendental meditation long ago, part of it was to do that in a sitting position, because one is likely to fall asleep when lying down. Years later when I started having trouble relaxing after going to bed, it occurred to me to try this, and it worked!
I hope these techniques work well for you. Feel free to modify them in whatever way suits you. The result will be a longer and better sleep. Sweet dreams!