The idea of picking up a horse's hooves can intimidate some owners since a well-placed horse kick would really hurt! Such caution is good, but in reality if you pick up a horse's hoof properly you provide him with no leverage or ability to kick you. This is a situation where a person's worst fears can cause him to imagine an incident that is highly unlikely to occur with careful handling.
Here's how to safely pick up a horse's hoof:
Starting with front hoof, approach your horse diagonally from his front so that he clearly knows you are there – you don't want to surprise him. Place yourself even with his shoulder and make sure to face his rear; you will both be facing opposite directions during hoof picking process.
Making sure that your feet aren't too close to horse's hoof, start running hand parallel to him down his shoulder and along length of his leg, finally stopping just above his ankle. Gently grasp ankle portion and click (or otherwise verbally cue him) to ask him to raise his leg. If he's well trained, that small cue will be more than enough and he'll do just what you requested. You're now free to begin picking his hoof.
If your horse is being a bit stubborn or hasn't learned how to pick up his legs yet try leaning into his shoulder as you run your hand down back of his cannon bone. You can also gently squeeze/pinch tendons to further cue him to what you would like. As you perform these physical cues make sure you provide a verbal one also (I make a clicking sound) so horse later associates your sound with requested response. Increase weight you push against his shoulder until he finally lifts his leg as requested.
When picking a horse's hoof you want to remove all debris from hoof clefts as well as rim and frog. Be careful around frog because it can sometimes be a bit sensitive, particularly if horse has thrush.
Once you have finished cleaning front hoof carefully guide it back to floor; you don't want to allow horse to slam it, potentially hitting your foot in process. Praise your horse and pat him on front shoulder a bit so he understands that you are pleased with his cooperation, then run your hand along his back to his rear leg. Place yourself in same position as you did with his front leg and do process over again.