How do you research a novel without drowning in it?
By researching to a question rather than to a subject, and by accepting that most of what you learn will not appear on the page — which is the point, not a waste.
Why research becomes a trap. It feels like work, it is comfortable in a way that writing is not, and it has no natural endpoint. Writers use it to postpone the difficult part indefinitely, and the resulting knowledge creates pressure to display it. Research anxiety and perfectionism are usually the same problem wearing different clothes.
A workable sequence:
Write first, at least a draft. You cannot know what you need to know until the scenes exist. Mark gaps with a placeholder you can search for later rather than stopping to look things up — stopping mid-scene is how momentum dies.
Research to specific questions the draft raised: what did this cost, how long did the journey take, what would they have been wearing, who would have been present.
Go deeper only where the story lives, which is usually a small number of places.
What produces the best material:
Primary sources — diaries, letters, newspapers, court records, catalogues, menus, advertisements. These give the texture and the small wrong-sounding details that secondary sources smooth away.
Physical experience. Walking the ground, handling the object, learning the skill badly for an afternoon. This produces sensory detail no reading gives you.
People who do the thing. Most professionals will talk to a writer who asks specific, respectful questions, and their offhand remarks are frequently the best material.
Maps, photographs and floor plans, which prevent geographic impossibilities.
How to use it without dumping it. The reader needs enough to believe, not enough to reconstruct. One precise detail conveys authority better than a paragraph — and confidence is conveyed by what you do not explain. If a character uses the correct term without glossing it, the reader assumes you know.
Get the emotional truth right first. Readers forgive a wrong date; they do not forgive people who feel invented.
Keep a source list as you go, for the fact-check you will need later.