Counter battery fire
Introduction of guns with self-survey and orientation has led to the concept of gun maneuver areas where the troops, platoons or sections of a battery keep moving around, although it is questionable how sustainable this is.
Concealment. While firing guns cannot escape sound-ranging and radar detection, concealment and deception can reduce the likelihood of discovery from other methods.
Counter-battery fire, being prepared to reply to enemy counter-battery fire with counter-battery fire of your own.
Human shields. The practice of embedding artillery assets within a civilian population to discourage enemy counter-battery fire, based on the assumption that a counter-battery strike would damage and destroy civilian infrastructures as well as killing innocent non-combatants. The legal protections afforded to non-combatants mean such tactics would generally constitute a war crime.
Of course there are many potential target nodes in the field artillery system, including those dedicated to finding hostile artillery. Attacking these may significantly blind the enemy's CB capability—counter-countermeasures.

See also: AMOS or Advanced MOrtar System
Archer Artillery System
Artillery Surveillance and Target Acquisition
Counter-battery radar
Counter Rocket, Artillery, and Mortar
Flash spotting

References: 

Sources: General Sir Martin Farndale History of the Royal Regiment of Artillery - Western Front 1914-18
Maj Gen AGL McNaughton The Development of Artillery in the Great War, Canadian Defence Quarterly Vol 6 No 2, January 1929
Peter Chasseaud Artillery's Astrologers: A History of British Survey and Mapping on the Western Front, 1914-1918
NATO AAP-6 NATO Glossary of Terms and Definitions