As mentioned above, it is preferable to appropriately introduce yourself to the horse before putting the halter on. It is good practice to put the lead rope around the neck before haltering. This gives you a secondary means of control if the horse resists haltering. With a less-than-cooperative horse, placing your hand on the front of its nose can also add to your control while you are getting the halter ready and putting it on.
You will generally need to be on the horse’s left side for several reasons. Horses are generally handled from the left side. Equipment has been developed over the years to accommodate this custom. The halters virtually all buckle or tie on the left, and so on. It is awkward, at best, to put a halter on from the right.
Some horses will very helpfully put their nose in the halter when you hold it out, many will not. Placing the headstall strap around the neck while you position the nose is helpful and gives you some control over the head. Once the noseband is over the horse’s nose, you can place the headstall strap behind the ears and buckle it on the left side. Sometimes the halter will have a clip on the throatlatch that attaches to the headstall. In this case, you can place the noseband over the nose, guide the headstall over both ears gently and then snap the throatlatch to the headstall.
The lead rope is over the horse’s neck/withers, in your hand or over your arm or shoulder throughout. It should not be dragging on the ground and absolutely not wrapped around your hand or body in any way. Be sure it does not present an opportunity for you or the horse to step on it or trip and become entangled. You will have time to practice haltering and leading during the workshop if this is new to you.