Quality, independent sources need to write about you or your company or whatever the subject of the article is. These can be mainstream publications or credible trade publications. Once notability is established, the range of sourcing for other facts in the article is somewhat looser.
We have an internal PR team led by well-regarded former journalists who have been intensely trained on Wikipedia notability requirements. We sometimes will take on a client that we believe has a story the press will respond to with substantial coverage. We focus our story pitching only on those mainstream publications which will be considered reliable by Wikipedia. The journalists we pitch are those we expect to do independent reporting and analysis (markers of an acceptable Wikipedia source), not press release rewrites (we don’t do press releases in any case.)
Positioning the subject with the right type of language and sources to support notability is critical. We have dealt with several subjects that were rejected as articles when originally submitted by a company or individual but then later approved after we offered a new article with better framing and sourcing.