When we experience difficult emotions like anxiety or nervousness, our scope of awareness becomes very narrow. We go on alert and orient our attention toward what is "wrong," we overlook a large part of our experience. One skillful way to respond to these mind states is to intentionally (and this will take some effort) expand our scope of awareness. Check out your environment for clues that let you know you are safe, look around or listen for things in your environment that are appealing to you in some way - notice the details and then check out the sensations in your body. When you practice in this way you are broadening your scope of awareness which offers a larger frame and can shift your perspective. You can start your sit with this type of mindfulness practice, and this will help settle the mind. You can also do this when you are engaged in daily life activities.
You might also ask, "what need is arising for me right now?" Check this out with compassion and curiosity. Simply asking this question can help provide a container and offer some ease.
You may also consider taking up a short daily gratitude practice. Practicing gratitude is a great way to build the habit of orienting to our experience with a broader perspective. Oren Sofer has a guided meditation on Gratitude in the Just Meditate section of the app. Also, this article offers a good way to learn about the practice: http://www.happify.com/hd/the-science-behind-gratitude/