I cheat. I use a bucket of feed. A+M feed or some pellets, you can even use chopped up apple and carrots. They learn that the bucket means some good stuff, and will usually follow that bucket any where. as a last resort use the feed bucket let the horse put its head into the bucket , while it is being held by the handle, and a lariat noose is held in line with the bucket, I used a cotton lunge line, and after a few tries the horse was 'caught' from there we got a halter on it. Now we did have a bit of a 'fight' and freak out, and make sure that the lasso wont choke the horse or you have an ever bigger mess .