It is highly recommended (though more difficult) to hike from here to Hidroelectrica rather than to Sta Teresa. The trail to Hidroelectrica is very well marked. You will have to climb for 3 hours then go down for 2 hrs to reach Hidroelectrica. Some 15 minutes after the top of the climb there are some ruins with amazing views to Machu Picchu where you can wild camp. This is highly recommended if you can time it so. If you decide to explore the ruins, watch out for rattlesnakes and tarantulas on the overgrown paths around. The same is valid for the whole hike in that area.
From Hidroelectrica it is 2.5-3 hr along the railway to reach Aguas Calientes.