An expert has what most advertisers do not: the ability to answer usefully. That is the acquisition channel.
Why it works
Advertising an expert invites doubt — claims about yourself prove nothing. Taking apart someone's actual problem proves everything at once: the reader sees the reasoning and draws their own conclusion. One precise answer in a discussion beats a dozen posts about your achievements.
Where to answer
Where questions get asked: professional chats, discussions under colleagues' posts, communities of clients. Look for your clients' venues, not your profession's — colleagues will not hire you.
What to write
A specific answer to a specific question, with no pitch attached. The sale happens in the profile, not in the comment: whoever found the answer competent will look at who wrote it.
The profile decides
A name, a clear line about what you help with, a link to a channel or site. An empty profile cancels the work before it: there was interest and nowhere for it to go.
Rhythm
A few substantive answers a day beat twenty perfunctory ones. Expertise does not scale by volume: recognition in one community is worth more than presence in a hundred. Automation handles finding venues and drafting; the last word stays yours. See the automation page.