It's nearly impossible to discuss WWI tactics, without basing that discussion around the rapidly changing battlefield technology of the early 20th century. Perhaps most telling, were the two new theaters of war; the depths, and the sky. Napoleon's weather balloon and the German Zeppelin airships were antiquated by the invention of flak, and other forms of anti-air artillery. Trench warfare (which you seem to have read about) was a notoriously stationary, deliberate, and attritious form of warfare that's success depended heavily on who held logistical, intelligence, and observational advantages. Thus, WWI is the first war where we see areal reconnaissance become an essential part of the contemporary war palate. Additionally, the nature of a trench rendered conventional artillery of the time somewhat ineffective due to its shallow arc; this leads to the readopting of the mortar (a weapon used as early as the siege of Constantinople). Arial bombing was also recognized as an extremely viable option for decimating an enemy trench. The use of tanks, armoured personnel carriers, and chemical warfare are also funded/ implemented as a response to trench warfare. Trench warfare served as a proverbial pressure-cooker for technological advancement, as both belligerents explored ways to break the stalemate - as we can see by studying WWII, battlefield tactics were never quite the same after.

Sources; Rumerman, Judy. "The U.S. Aircraft Industry Durin World War I." U.S. Centennial of Flight Commission. Zabecki, David T.: Military Developments of World War I, in: 1914-1918-online.