Good: ‘killing your darlings’, ie cutting things that don’t serve the story even if you love them, is a very valid idea. The trick is knowing what serves the story (tip: it’s not synonymous with ‘advances the plot’)

Bad: any kind of prescriptive story structure. Hero’s journey, story circle, save the cat, etc.

Ugly: ‘write every day’. Not everyone can, and not everyone benefits from it. Touch grass.

While writing every day is good advice for some, I think a broader and more valid idea is working on your craft every day, or regularly. This can mean writing (and you do have to do a lot of writing to become a decent writer) but it can also include:

• reading;
• pursuing and having the kinds of experiences you want to write about;
• intentionally and mindfully observing. If you find yourself at the edge of a conversation, for example, try to really actually listen to how and why people say things. Sooooooo much bad writing gives off the vibe that the author only knows anything through other people’s writing.

Oh also: “write what you know” is right but you need to remember that not only do you have the power to expand the breadth of what you know, doing so is an essential part of writing.