Niche down until it feels too narrow
Most bloggers choose a topic that is too broad. Successful blogs are not about "fitness" but "strength training for women in their 40s." Not "travel" but "budget solo travel in Southeast Asia." Not "personal finance" but "building wealth on a teacher salary."
The narrower your niche, the more your content resonates with exactly the right reader — and the reader who feels exactly understood subscribes, shares, and returns. You can always expand once you have an established audience; you cannot build one by being generic from the start.