This is really a key part for anybody who has lots of ideas (the other key part, as you say, is actually DOING the remaining ideas, that's much harder!).
When I finally managed to get away from hourly-paid computer consulting about 5 years ago I thought the most important part was to design the lifestyle first, and then design the business ideas to fit that. Not be forced into a lifestyle I'd hate. So I set myself three rules, which are essentially what NOT to do:
1. NO employees, ever. This immediately rules out many businesses (most retail, larger forum and community sites, anything that bases income on reselling time). But was essential for me, as I'm not a manager, and I know it.
2. Work where and when I want. No (tele)commuting with fixed deadlines, no visiting customer offices, no having to be present anywhere at a given time basically. Of course taken to an extreme this results in no income, but the key thing is it's MY choice when I work (if at all).
3. Business must fit in an airline carry-on bag. Part of the "work anywhere" really, but emphasises that no business idea can include a fixed location (like shipping and returns, unless outsourced), and cannot buy bulky capital equipment (one of the most dangerous temptations for a new business).
So that leaves me with businesses that can be done "off-line" (not on a schedule) from anywhere. Given my background, it's developing my own advertising-supported websites (with the focus on evergreen reference content, not current news), and trading in domain names.
If you set yourself (probably different) rules that fit your intended lifestyle, you can limit your ideas to the ones that fit, and toss the other 90% away.
For example, for some a local community website, plus making websites for local business, perhaps for people you've known all your life in a small local area, would be a great fit. That person would turn down jobs in the "big city" 80 miles away, and jobs on subjects that are outside their experience, and be happier for it.
Having said all this, I still have the remaining 10% of ideas left and still only get to 1% of those! For older websites, it's easy to justify "if it's not broken, don't fix it" but this does mean I have a (successfull, profitable) website that I've been going to update "next month" - since 1996!