1) Offer a sidebar/plug for their website. Especially effective if you have good traffic.
2) Ask interesting questions, pick interesting topics or story angles. Most interviews are trite, asked-a-thousand-times junk.
3) Offer advanced review of questions and to rework them if needed. You don't want a puff piece, but offering to rework questions for a better article can get an interview subject off the fence. Ask them, for instance, what questions they wished they were being asked -- what misconceptions there are, etc.
If the interview is well written, your subject may link to you and send traffic your way. The only way to do this is to research the topic and whoever you interview to find out the questions to bring out new angles.
Poor: How to you work with clients?
Better: What are three things web design clients would be shocked if they knew you could do for them?
You must word the question to provoke an informative answer while structuring it to produce an answer compelling to readers. Straddling these two perspectives is no easy task. Poor questions are boring to read, and more boring to answer.
A note about buzzwords: Make sure they're words customers search for. One SEO describes keyword research as the "cold shower moment." Where, for instance, web designers search for the buzzword -- not the web design clients you need to sell. Often the buzzwords a company swears by aren't what best customers search with.
When you use buzzwords, make sure you aren't using the interview as an excuse for keyword stuffing. Explain the "hidden secret 'they' don't want you to know about [insert buzzword here]. Give a brief definition or otherwise explain what the word means.
Too often people use the words but don't understand them. I was interviewed -- the employment kind of interview -- by a web design company. I answered the several dozen questions they asked, but they couldn't answer mine:
....What's a tactic, what's a strategy? -- how are they different and give an example.
....Describe how you develop a content driven website?
....What's information and how is it different from data?
...What's content, and how do you "manage content?"
If you want to get an awkward silence, trying interviewing web design agencies about anything other than buzzword compliance. Try asking what the buzzwords mean.