You can find cross-border bus from Guangzhou to Macau. Or you can take bus from Guangzhou to Gongbei, Zhuhai and then go through Gongbei Border to enter Macau. Hotel Central- Macau is comparatively cheap in Macau. You may consider about it. From Macau, you can go to Macau Marine ferry terminal to take ferry to HK.
When travelling in Macau, you should not miss the Venetian, St. Paul's Ruins, Senado Square, A-la Ma Temple and Fisherman's Wharf. While travelling in Hong Kong, you should not miss the Ocean Park, the peak, Ngong Ping 360, Repulse Bay, Temple Street, etc.