Foreigner Going from Shenzhen to flight in Hong Kong

You are going from SZ to HKIA for an onward flight to Guilin, right? You may take a bus to HKIA from Sunshine Hotel, The Panglin Hotel, Best Western SZ Felicity Hotel, Crowne Plaza Longgang, Century Kingdom Hotel, Luohu Hotel, etc. The fare is HKD 200. The trip takes about 2 hours. As I konw, you need to go through customs.

BTW, why not you go to Guilin directly from SZ by air or high speed train (3.5 hours)? It will be trouble-some to make a detour in HK.