How are you finding rising websites and niches before they become obvious?

Curious how other people approach this.

When you're trying to spot a rising website or niche early, what do you usually rely on first?

I’ve seen a few different approaches:

- keyword tools

- trend data

- competitor tracking

- related-site research

- watching groups of websites in the same space

What tends to work best for you, and what usually helps you tell the difference between a real trend and short-term noise?