You could go to the Shangxia Jiu Road or the Beijing Road, both of which are the famou shopping streets in Guangzhou. You could hire a cab to reach there, almost every drivers know them well.

You can get to Tianhe area or Zhanxi Road. Tianhe is closed to Guangzhou East Railway Station, which can be reached by train from Hung Hom Station in hong Kong. Zhanxi Road is near Guangzhou Railway Station, there are many wholesale markets. Shangxiajiu and Beijing Road is closer to Guangzhou Railway Station. Not far away from Subway Line 1. They are well known business streets in Guangzhou. You can get to Guangzhou Railway Station from Guangzhou East Railway Station by subway lines. Excep those sais above, there are Yuexiu Park, Liurong Temple, Sun Yet-San Memorial Hall, etc.

Hi Andrea,
If you come over from Hong Kong, you can take a taxi ( as well as subway if you'd like to try) to Tee Mall ( Tian He Cheng in Mandarin ), it's near the Guangzhou East Railway Station. Then in the afternoon, you can take a taxi to Beijing Road Pedestrian Street. Many shops and restaurants in the above two places. Beijing Road Pedestrian Street are with less expensive prices. Good luck!