A B737 flight crew taxiing north on AUS Taxiway C turned right on Taxiway S instead of Taxiway H. The night time conditions and no illuminated Taxiway S signage on Taxiway C caused confusion because Taxiway H signage was sighted near Taxiway S.

Narrative

After landing on Runway 17R at AUS we were given instructions to taxi to the gate via T-C-H-G2. I proceeded north on C and turned right onto (what we both thought was) Taxiway H. However; I had turned short of H onto Taxiway S which was an empty; darkened ramp. When we relayed to Ground Control that we had turned in error they said; 'It happens all the time' and told us to make a 180 degree turn and proceed back to C. As we proceeded back to C we looked and saw that for northbound traffic on C there appears to be no sign for Taxiway S and the sign for Taxiway H is very close to Taxiway S. In the darkened sea of blue lights that exists in this area; it is easy to see how this sort of error 'happens all the time.' The problem is that it is so dark in this area at night that if one got distracted for even a few seconds they could easily go off the edge of the ramp as it comes up quickly after making the turn onto S. There obviously needs to be a sign for S for northbound traffic on C in this area if this problem occurs frequently. Especially if the sign for H is so close to Taxiway S as the H sign gets lost in the darkened sea of blue lights also. When taxing southbound on C approaching from the north of H there is a sign for S; but not when coming from the south of S northbound. Perhaps it is there and we both missed it or its lights were out but we looked while taxiing back to C after our 180 degree turn and could not find it. Until then only having made the error once will prevent me from doing it again. Not so sure for other pilots.