Reasons for Involvement

In 1914, Russia was bordered by Germany and Austria-Hungary who formed a defensive alliance called the dual alliance; if attacked by Russia, they’d come to each other’s defence.
Russia and Serbia also had an alliance (unofficial), showing that Russia was trying to assert its influence abroad.
Outbreak of WWII: Austria-Hungary invades Serbia, Russia joins and declares war on Austria-Hungary, and Germany then declared war on Russia — surprised Tsar Nicholas II as he believed his family ties with Kaiser Wilhelm II of Germany would supersede international treaties (cousins)

Early Stages of WWI

WWI offered some respite for the Russian royal family.

Russians were patriotic to the war: Russians were keen to see their leadership defend them against foreign attackers and thousands gathered outside the winter palace to show support for the Tsar; 95% of men conscripted into the army turned up willingly for duty
Weak mobilisation: the army was mobilised extremely quickly but were unprepared, some soldiers fighting without boots and rifles
Slow industrialisation meant not enough production of weapons or ammunition to supply the troops
Poor strategy: military strategy was weak and outdated, Russia only had a defensive war plan so when Russia was on the offensive, military commanders were clueless

Early battle failures; in August of 1914, invasion of German East Prussia, Russia was defeated at Battle of Tannenberg. In September of 1914, another defeat at Battle of Masurian Lakes. In May of 1915, Russians forced into retreat, and in the middle of 1915, approximately 800,000 Russians died.

Tsar Nicholas commands the army; Tsar fires army commander-in-chief and stepped in due to defeats and lack of progress. Tsar abandoned Russian homefront at a time of crisis and left Russia’s leadership to Tsarina Alexandra, and the Tsar took on responsibility for the war failings personally and lost support