Since I talk about the difference between history as a hobby and as professional research reasonably often, here are books I think you should read if you want to think more about how history is created:
Time’s Monster: How History Makes History by Priya Satia
Metahistory: The Historical Imagination in Nineteenth-century Europe by Hayden White
Silencing the Past: Power and the Production of History by Michel-Rolph Trouillot
The Past is a Foreign Country by David Lowenthal
Along the Archival Grain: Epistemic Anxieties and Colonial Common Sense by Ann Laura Stoler
Dust: The Archive and Cultural History by Carolyn Steedman
If other people have books they would consider key, please add them. It might be good to start a longer list.