Quality is attractive, make it public visible. If have a blog, write about excellent questions and answers on the site, quality is attractive. You could even post a storypost a story on hacker news, reddit, or stumbleupon. Share links to great questions.
Seeing an own difficult question answered here, is attractive. If you notice that a TeX hacker raises a question via twitter, facebook, mailing list, Usenet, or web forum and you see there's no good answer yet, post the question here. Help her or him to get the answer. Of course include a link to the source.
Make package authors interested by questions and answers which can improve the package or the class.
Directly invite TeX experts, for example as interviewee or guest author in our upcoming TeX.SX blogupcoming TeX.SX blog.
Go where the TeX experts are, show up at TeX conferences and local user group meetingsTeX conferences and local user group meetings, talk about TeX.SX.
replaced http://meta.tex.stackexchange.com/ with https://tex.meta.stackexchange.com/
replaced http://meta.tex.stackexchange.com/ with https://tex.meta.stackexchange.com/