Hi adara,
Himalaya book stores(Panjagutta,Nampally,Khairathabad)
Odessy(Jubilee hills,Somajiguda)
Walden(Begumpet,Banjara hills)
These are the few book stores with good collection of novels.
Can try and explore the sunday second hand books sale on the roads of koti,Abids.
For the information about libraries,check out
IL Directory/Hyderabad/Libraries