Here are some concepts I learned concerning "how to study history."
I graduated from Vanderbilt University in 1960 with a degree in Chemical Engineering and worked thereafter at jobs that utilized my training. So, the Scientific Method of study is a firmly ingrained habit. Given a choice between seeking politically correct truth, versus scientifically correct truth, I always select the latter, even if it is uncomfortable. Also I have always been wary of drawing a conclusion from one set, or even a few sets, of data when more observations are needed to justify it. So my study invariably needs to be deep, needs to seek proof of accusations and claims. I am especially suspicious of propaganda, fully recognizing that "it is the victors who write the history of military and political conquests."
I believe it imperative to abandon thoughts of today and of modern times when studying history. To study history you need to mentally transform yourself to the time period being studied, and mentally take on the life of the people under study, for only then can you understand history from their perspective. It is based on the events of the time that I evaluate the actions of men, and the history those actions produce. I always remember that different actions would produce a different history than the one of which we are the children. But we can only speculate about how that alternate history would be different. And speculating on such matters is just playing the "what if" game. I generally focus on the goodness or harmfulness of the means, with little regard for the ends that result from those means. I do not agree that "the ends justify the means." When it comes to history, I study the process more than I study the outcome.
I believe assigning the most correct name to an issue helps a student understand the issue, and the related issues as well. I am troubled by words that political advocates choose to promote their particular political agenda. Two thousand five hundred years ago Confucius, the noted ancient Chinese philosopher, concluded, "To understand an issue you need to call it by the right name." I use that simple but profound rule during study of history, renaming when I need to enhance understanding. For example, I keep separate the three different political movements that are normally grouped under the term "anti-slavery." I rename them individually as "Exclusionism," "Deportationism" or "Abolitionism."
It imperative to follow events chronologically when studying history, to ensure you correctly examine actions, reactions, actions, reactions, etc., all in the proper sequence. Otherwise you are easily deceived into gross errors, such as identifying who is an aggressor and who is a defender.
With the study of politics and politicians it is especially important to look at actions, not at words. Politicians often claim to advocate a policy to win favor, but never act on that alleged advocacy. So I read the words delivered in speeches and consider their meaning at that particular time, but it is the actions that primarily produce my understand of the man and what he stands for as time goes by, and as his positions adapt to changing times.