Trump says CNN, NBC, ABC and CBS are fake news; so what are the "true" news sources that conservatives believe are accurate and factual?

You're making it too simplistic. While those sources you noted above absolutely have a tendency to report incomplete, unsubstantiated, and even downright false reports, they are still sources I use. Much in the same way I look at Fox, when I read something too good/bad to be true, I dig deeper and I look at the report as objective as possible to see what might be missing. Finally, I also try to look at it from the perspective of both sides, asking myself how would I look at this report if I were coming from the left/right's perspective. The media has done itself a huge disservice recently in their attacks against Trump. Seriously, had this level of rhetoric, unnamed sources, and focus been directed at our previous President, everyone of the responsible media sources would have been branded racist and "fake" just the same.

My perspective as a conservative, I like fox because they report more about things I care about (call it the right leaning bias if you will). At times, I think they too push incomplete and unsubstantiated reports (although I think they do it less than many other sources lately). This is not to say I don't read or watch other sources. I like to know what they other side pushes, what they may neglect to report, and what might lead them to push that report. Gotta say, Trump may not be good at pointing out the bias and calling out the media's irresponsibility, but he does have a good point and the right to defend himself when attacked.

So to answer your question more directly, I look at any and all sources for any and all the facts I can extract. Sometimes this requires multiple sources (including the ones you named) to get the whole picture. What I find humorous from many of the folks who post here is, they post an article as the truth to fit their narrative, but many times they don't even read or absorb the whole article. Furthermore, they also don't take the extra step to be a little objective and see if there is more to the story. All they do is copy/paste links from the most bias sources while failing to do some easy research which even those same sources failed to do. When I choose to post a link, I tend to purposefully find one from a source other than Fox or conservative leaning sites. I even conducted an experiment once by linking to a Fox URL, to which many immediately dismissed as biased because it's Fox. After a few of their dismissive posts, I then pointed out that it was an AP article posted by Fox. My point here is, don't pigeon hole yourself into a single source and debate your own preferred narrative before you decide to post the source as what you see to be 100% truth.

There's opinion articles that jump to conclusions, and there's news articles that contain facts with an opinion leaning towards an agenda. One should learn to read between the lines, filter out emotions, and opinions while formulating your own.

As I lean center left, I read right-wing articles so I can get a different perspective and have a middle grounded opinion.

I often like to check news from BBC. They're more likely to report US news without as much political leaning in either direction so a bit more factual.