It is perfectly natural to have times when you miss home comforts, family, or friends, especially if it is your first time travelling abroad alone. As well as comfort foods that you bring with you from home, western restaurants and groups of expats, especially other foreign teachers in your school, are there to help you feel more at home and relaxed. Throwing yourself into activities and meeting new people can often help lift you much more than staying in your room and calling home. That said, it is good to keep regular contact with home (even if more for your parents than for you!).
Get your family and friends to download WeChat before you come to China. WeChat will be a much more reliable mode of communication than WhatsApp or other messaging services which are often blocked or slower in speed in China. Remember: you will need a VPN for Facebook, Twitter and Google, making them slower than normal, and while Skype does work, it is not as reliable or efficient as WeChat.