Guidelines:
- Find a good niche
- Be comfortable being very public presence in that niche (blogging, speaking, etc)
- Develop a way to present your niche to stakeholders, not just technologists. Be comfortable writing persuasive writing to convince people they need your service (both w/ proposals and marketing)
- Genuinely care about your clients & their success
The tricky thing is to be a well known name in your niche is the "sweat equity" of consulting, it requires a lot of work and late nights & weekends. Does it take writing a book? Or just traveling to a bazillion conferences, blogging, upping your social media game? Building lots of relationships? All of the above? It can take a lot of work to get established.
Eventually you'll begin making connections to prospective clients (this is as easy as a single sentence reminding people you're a consultant). At first, you'll take what business is there, and do your best to make your first batch of clients successful. At this point, you'll have to divorce yourself from being so focused on pushing all your time into being "tech thought leader" and find a balance between that and the day-to-day client work that pays the bills.
Balancing the two turns out to not be too hard if you take the attitude that your early-stage work (marketing and sales) is about caring about prospective client's success before you meet them, not about you pumping yourself up. You genuinely care about how aluminum widgets should be used in glem refractors, so you are eager to teach the market about it. Clients with particularly tricky glem refractor problems know you're the person to talk to.
Finally you'll gradually work up to more and more sophisticated clients, doing more and more interesting work. If you're turning down 90% of your prospective clients due to time constraints, that's a sign to raise your rates a lot. It's expected you'll filter out the riff-raff with higher rates - these were the clients that don't want to invest in your domain anyway, you-the client probably aren't a good fit.
You should be prepared to reach a point in complexity where just one consultant w/ no support might not be sufficient. You'll need to have a good team and back-office: contracts, lawyers, invoicing, etc. You really need to think hard about cashflow and dealing with non-payment :'(. With more experience and a bigger team, you'll begin to see things that are reproducible and can be repeated, and can market those as productized offerings for your market. Return to the marketing & sales side, rinse, repeat.
Every round here is a level of increased sophistication, more sophisticated and challenging clients, and opportunity to really push yourself. But it's not for the feint hearted - do it because you really like your domain & serving clients. Expect to need to treat consulting as a craft in-and-of-itself, regardless of content area. Also expect that technology has its limits in how much it can help orgs. So many client issues really are organizational in nature. You'll need to think about how the organizational/people aspects intersect with the technological.
Of course happy to give you 30 mins of my time to chat about our experience - feel free to reach out http://o19s.com/doug