At the start of the First World War, aviation was primarily limited to observation roles. With no practical experience, even in this seemingly basic operation, techniques had to be improvised and improved upon as more missions were flown. Often, the pilot would land next to the command tent, jump out of his plane, and report his findings. However, aircraft proved more valuable than observation balloons, which became easy targets for the soldiers on the ground. 

This British B.E.2 is typical of crude basic aircraft used in the first months of the war to perform observation duties. 

In the first months of the war, the aircraft did not have armament, with the pilots often bringing side arms or rifles into the air with them, with little chance of hitting the enemy on the ground or in the air. Similarly, aerial bombing was attempted, which amounted to little more than tossing artillery shells out of the planes. 

This German Taube, like many aircraft in service at the start of the war, was slow and had limited maneuverability.

The French used all available aircraft for reconnaissance duties, including the Bleriot XI.  The San Diego Air and Space Museum has a reproduction of the type on display.

One aspect of air combat in the early months of the war that proved effective (more so in terms of spreading fear and causing reallocation of resources than causing physical damage) was Germany's use of Zeppelins to bomb Allied targets. The first such raid occurred on August 6, 1914 when L VI bombed the French city of Liege. Although such attacks caused panic among civilians, the Zeppelins proved to be vulnerable to air defenses and many would be destroyed over the course of the war. 

French citizens inspect a Zeppelin that was brought down during a bombing raid.