Bus is most convinient, I think. Guangzhou's Tianhe and Guangyuan passenger bus stations has direct buses to Macau. You can also find buses in some hotels, such as Dongfang Bin Guna, Huaxia Hotel and so on. It cost about 65 RMB. You can also try the airport bus to Macau Airport. I know Garden Hotel, Huayuan Jiudian in Chinese Pinyin, has airport buses there. Or you can take buses to Gongbei Pass of Zhuhai by bus, after passing through Gongbei, you are just in Macau.