Some of your customers now ask an assistant instead of searching. They describe a problem, they get an answer, and a few sources get named. Nobody can tell you how to be one of those sources reliably. What is visible is the shape of the pages that keep turning up in the answers.
Write paragraphs that survive being lifted out. An assistant quotes a passage, not a page. If the paragraph only makes sense after the two above it, it cannot be used. Each one should name the subject, state the point, and stand on its own if somebody pasted it into a message.
Put the answer before the context. A question, then the answer in the next sentence. Background afterwards for anyone who wants it. This is the opposite of how most service pages are written, where three paragraphs of positioning arrive before anything is stated.
Be the source of something checkable. Assistants reach for pages that contain a specific fact, a number, a procedure, a price. A page of adjectives has nothing to cite. If you publish the actual steps of your process, or what a thing costs, or what you found in fifty audits, you have given it something to quote.
Keep the plain version on the page. Text inside images, video, or a widget that loads after the page does is text that most crawlers do not see.
There is also llms.txt, a file at the root of your site listing your main pages in plain text. Support for it is not settled and it may not be read at all. It takes twenty minutes to write, so we add it and move on rather than arguing about it.
Two things worth saying plainly. Nobody can guarantee that an assistant will cite you, and anyone who does is selling something. And this work overlaps almost entirely with writing clearly for people, which is the part that pays for itself whatever happens next.