My experience is rather limited, but my experience with niche sites tells me that the money should always come LAST. Here's how I prioritize my steps for building niche sites:
1. Find a good niche (keyword research, surveys, etc.).
2. Put together great free content.
3. Put together a piece of content (an ebook, a course, etc.) you can use to get email signups.
4. Get email signups.
5. Build a great audience (social media, search, etc.)
6. Ask your audience what they want and would pay for.
7. Build it.
8. Sell it.
I see a lot of folks new to IM and niche sites that start off with, "How can I make money with this?" The problem is, you really have no way to know until you have an audience. The value of your audience is in more than their pocketbook - it's in their brains! A good audience will tell you exactly how to take their money, and there's no substitute for audience feedback and input.
The fact is that the "money last" attitude is counter-intuitive. My own husband used to drive me batty; I would tell him about some neat new feature to my site and he'd always ask, "But how is that going to make you money?" The truth is that if the audience is there and you're solving a problem for them, you'll make your money.