A decent portion of designers' knowledge will probably come from blogs, articles, and things they've read. This is no bad thing as each person is limited on what they can work on and by sharing learnings we can all benefit from each other's experiences. There are obviously several types of written content but I’m referring to those that describe an experiment or improvement you could cite as evidence for making a design decision.
Many companies from startups to big corporations are good at writing up what they've discovered in the process of researching, designing, developing, and launching their products. Often they can be useful for preventing you making mistakes others have already made. However you do have to exercise caution as not all content is created equal and you can use this learned knowledge inappropriately.
For this method there’s no real fancy process. You can build an RSS feed; create a list of trusted sources on Twitter; sign up to a selection of mailing lists; even subscribe to magazines (old school). Many podcasts are good sources to learn from too. Whatever your method, by setting up a regular delivery of content you save yourself having to go hunting for it, instead it finds its way to you.
I'm a big fan of the serendipity of Twitter and the chance to get content from publications you wouldn't otherwise look at in your stream. It's also very current but the downside is it tends to suffer from a lot of noise.
When it comes to the article content itself, there are some things to think about before deciding whether to apply the learnings to your product or company. You don't want to go telling everyone in your company you should do something and citing an article as evidence if it doesn't apply to your situation.
How solid is the data? When blogs make big claims about how they 'increased conversion by 50% with one simple change' it's always worth asking how they measured that before rushing off to apply their findings. You may not get the full raw data due to privacy concerns but you should be able to get a sense. Was it a test of flat designs with 10 people or was it done as an A/B test with tens of thousands of users? If the former, take with a heavy pinch of salt and if the latter you might decide it's worth looking into. It doesn't just have to be based on large sums of quantitative data, if it has been learned through several rounds of user testing, that is also high quality research.
Is their business comparable? Are they in a completely different sector, have a very different target audience, or at a very different stage of growth to yours? If so then what they describe may not apply to your product at all. A blog from a startup aimed at millennials that describes the perfect mobile navigation is unlikely to apply to enterprise software for the financial sector.
What's their motive? Plenty of companies just share what they've learned as a matter of giving back to the community but there'll be some articles you come across that are actually companies trying to push their software. In which case their software usually turns out to be the perfect tool for the job or the hero of their story. It's usually fairly obvious but can be done subtly using paid writers on third party sites.
And generally be very wary of articles that make broad sweeping statements about one design being better than another. I've lost count of the number of people who have asked me what the best colour for a button is because they read that "green increases conversions". Of course there is no such thing as a 'best colour' for conversions as it is going to depend so much on where it is positioned and the colours used around it.
Ultimately there are so many variables that it's hard to carry across statements about what would work on your site. But this doesn't mean you shouldn't keep reading, learning, and getting inspiration for ideas though.
One tool that is highly useful for getting through lots of articles is Pocket. Install the plug-in on your browser and the app on your phone then when you come across something interesting on your desktop with one click it's saved to your reading list on your phone for a quiet moment.
Reading an article doesn't tend to take long but this is something you can dip into at any time.
The following websites feature generally well-researched articles, useful for UX decisions:
Note: the examples in this guide are for website design, but most of the content is also applicable for native apps and software.