First and foremost, you need a couple of halters and lead ropes. Even if you have only one horse, keep extras on hand in case your horse breaks a halter or lead.
Halters are generally made of leather or nylon. Leather halters are the most expensive, but if you are going to buy one, buy top quality. The fittings should be brass, and the leather should be soft and strong. Seams should be double stitched, not screwed or tacked together.
Halters made of nylon webbing are the most common and least expensive. They come in a variety of colors. They are stronger than leather halters, which is actually a strike against them.
If a horse gets caught on a fence or hay feeder and struggles, a leather halter may eventually break free, but the web halter will not, and the horse could seriously injure himself or even break his neck. It's safer to remove any type of halter when the horse is loose in its stall or pasture. However, nylon halters do come in breakaway models, which have a leather crown piece that should break during a struggle.
You can never have too many lead ropes. Lead ropes are typically eight to 12 feet long and made of leather, cotton, flat webbing, or poly rope. They all last about the same length of time — which can be years, unless you leave them out in the rain consistently. You can purchase a halter and lead rope in matching colors. The important matter is how the lead rope feels in your hand.
Lead ropes with chain on the end are intended to wrap around an unruly horse's nose for better control. However, if you teach your horses to be respectful and behave while being lead, you will not need the chain, which just gets in the way in regular use.