MALE SOLO TRAVELLER, VISITING GUANGZHOU, FOSHAN, SHENZHEN, SHANGHAI, BEIJING & XIAN SEPTEMBER 2014

As I have no idea which city you will fly into and get back, here is just my general suggestion. You can travel in this order: Guangzhou - Foshan - Shenzhen - Shanghai - Beijing - Xian

Between Guangzhou and Foshan, you can take a train, bus or subway to travel. Then to Shenzhen, you can take a bus or train to arrive or go back to Guangzhou to use a high speed train to get there. After that, high speed trains/ normal express trains as well as direct flights are available for the left trips.

If u can search any international youth hostels in these cities, you are recommended to book. It will save you much money. Apart from that, you can easily find the chain hotels/Inn in these destinations, like Home Inn, Jinjiang Inn, Hanting Express Hotel and Seven Days Inn. They are not expensive either.

For must-sees, here is what I know:
Guangzhou: White Cloud Mountain, Memorial Hall of Sun Yat-sen, Yuexiu Park, Pearl River, Shangxiajiulu pedestrian and Beijing Road.
Foshan: Ancestor's Temple, Xiqiao Mountain
Shenzhen: Window of the World, Splendid China and Folk Cultural Village, Dameisha or Xiaomeisha resort, OCT East and Dongmen pedestrian.
Shanghai: The Bund and Huangpu River, Nanjing Road, Yuyuan Garden, Zhujiajiao Water Town
Beijing: Forbidden City, Summer Palace, Temple of Heaven, Badaling Great Wall, Ming Tombs. Bird's Nest and Water Cube
Xian: Terracotta Warriors, Huaqing Hot Spring, City Wall, Shaanxi History Musuem

As your itinerary is a little complicated and takes a little long, I recommend u join an independent tour from a travel agency. They will book and arrange all for you and you can still have a solo travel in China.