The other hand should be under the cat's belly, right behind the front legs. This allows for maximum control. Be sure the leash is hidden. I prefer to have it folded up in the wrangler's hand at the collar position. They're made of rolled, soft fabric, are very sturdy and fold up really small.
Owners tend to buy stiff leather or brightly colored flat nylon straps.
If you buy a dark color lead, it won't show the dirt from sweaty palms gripping it tightly. However, you may want a white one too, for those snooty cream-colored Persians done in high key. The leads are easily rinsed out in the sink. Remember, you are smarter than the cat. A wadded up piece of paper works well also.