We have a staggering number of primary source databases! Take time exploring them in your field/topic.
Language has changed over the centuries, and it is often difficult to speak like - and think like - our 17th century ancestors.
Words like college, race, "Indian," meant different things, and concepts like gender or nationalism didn't even exist.
As an example, a search for "gender" in Colonial America only yields 2 results, and only then relating to grammar rules.
Most primary source databases will have "thematic" filters to get you started. Before keyword searching, start there. See what curated documents come up. From those documents, see what terminology is being used by contemporaries.
Begin with basic searches and do not be too complicated. DO NOT USE TOO MANY TERMS AT ONCE
Be sure to use period-specific language.
Do NOT search a bunch of terms. This will give more, not less, false its.
EBSCO
ProQuest
Gale
WorldCat
GoogleBook
British History Online
Some Database like Chronicling America have a special drop-down feature for proximity searches built into the search commands.