Consulting leads who have found you on a message board are just shopping. You're offering a product, they kicked the tires a little, they decided not to buy today. These were cold leads, and busy people, so I wouldn't take it too personally. This is how sales works. You now share a bond with every other salesperson in the history of civilization.

One thing you can do is: follow up. This is what books like Get Clients Now! will tell you: The secret to making sales is to follow up, and to create systems for remembering to follow up. Give it a week or two, then write back to these folks: "We spoke the other week about X, and I wanted to make sure that you found what you were looking for. Are you still looking for help or all you all set?" It's okay to keep this very short. It's just a reminder, a sign that you still care.

One reason why you follow up is that a lot of these shopping expeditions just sort of get lost in limbo. Maybe the problem receded in importance for a month. Maybe they're short on runway and are hunting underneath the sofa cushions for loose change. Maybe someone just forgot.

As Patrick mentioned, as a newbie to this line of work, I have a slight fear of "annoying" people with follow-up contact that I need to get over.

Thanks to all for the helpful words of advice.

The problem is that whilst you're giving a timely and informative reply, it's just that; you're still just a name, albeit now with a tiny bit more information.

What really swung things around for me was always pushing for a Skype or in-person meeting, the latter being ideal, but Skype being a decent substitute.

This meeting lets you both size one another up, and figure out how you might work best together.

And, for that matter, whether the project, client and consultant are going to be a good match!

One other "so obvious in hindsight, it's painful" moment: never, ever, ever tell a potential client "I'm sorry, I'm fully booked for the next X months."

Instead, have the initial meeting, see how things go, and just simply tell them that you're available from day X.

If you're a good match, the client will wait.

Finally, my number one tip on how to really stand out of the crowd?

Reply to the initial inquiry fast, as in minutes after receiving.

You only need to say "Thanks for getting in touch, is it OK if I get back to you with a proper reply later on today?"

Given the incredibly poor communication habits of the average programmer on the street, small courtesies like this really pay off!

(For the peanut gallery: "Lead qualification" means figuring out whether someone is worth your time to sell to. For example, most startups are not in a great position to require my services or, to be blunt, in a position to pay for them. If one hypothetically sent me a cold email out of the blue, and I had consulting availability, I'd research/ask to figure out whether they were at a certain level of success/sophistication, whether the person contacting had decisionmaking authority, and whether they had high five figures in the budget prior to having a sales talk. If they didn't, I'd probably still offer to have a chat, but it would be a "I like talking to startups and would love to give you a few pointers" flavor of chat rather than a "I am intrigued by your company and would like to discuss a few ways by which we could work together" flavor of chat.)

This is absolutely worth repeating, or even printing and sticking on the wall.

Developing a nose for these sorts of good-but-busy clients takes time, but they can often turn out to be the best clients as they're the least likely to meddle and the most likely to schedule tight, productive calls with you.

You don't need this advice, but for anyone struggling to deal with busy leads, you need to ratchet down the complexity of your communications each time you get in touch. There are absolutely busy clients who won't/can't respond to complex e-mails that are wisely trying to assess a situation, ask questions, etc... but who will instantly approve a $10k order on the back of a very simple "Would you like us to do X? It'll cost Y" style of question. It's happened to me! :-)

Other than that, people are really busy (especially if they're high-ranking like you say). You can always send a follow-up email a few days later confirming if they had received your last email & play the "I'm trying to lock in my availability for the next few weeks" card.

Recommend reading How to Acquire Clients by Alan Weiss. Also, Strategy and The Fat Smoker by David Maister.

But, if I need someone "expert/dependable/fast" I'll ask my peer network. Considering your marketing strategy, areas to explore: Who are your best buyers? How do you reach them? How do they reach you?