One thing that ends an approach quicker than Ellen DeGeneris ends a fish burger is your "zoning". I discuss all these things in-depth inside the course but in short when learning how to approach a woman you need to be in the "Social zone" which is standing about 0.5m - 1m away from each other.
Often there can be a lull in the conversation and both of you realize that you're standing about a step further away from each other than real friends would when they talk. This will just reassure to both of you that you simply don't have the level of rapport friends have, let alone lovers.
It's just bait for awkwardness and worst of all when you're stretching over to touch her on the side of shoulder, forearm, tough or even face it looks very unnatural and forces.
Yes this type of touching is appropriate and it is essential for knowing how to approach a woman and keep her attracted to you.
Her physical tough-wires are too potent to neglect and the earlier you start building up your touches from: getting her attention when opening, to using touches for emphasis / gesticulation then to helping bolster your verbal advances and mimic them physically.
All things essential to getting her hot fast and if you can't do it fast and effectively then every minute more is a greater risk of losing her.