1.Learn something that has nothing to do with writing--often. Take a gardening course, photography, dance, archaeology, religion, anything. Career writers must have compelling things to write about. Am I the only one who notices how often novel characters are magazine editors, journalists, and writers? Dentistry, law, accounting, welding, real estate, sales, plumbing, jewelry making, fitness. It doesn't matter what it is and you don't have to become an expert but keep learning and trying new things. All of this will add a wonderful, genuine richness to your writing.
2.Avoid echo chambers. Turn them off. OFF. Yes, this means you social media but there are other echo chambers out there. For example, I live in a small community and after a while I notice everyone can start to sound and look the same. This is my personal bat signal to get out to a larger city for a while by signing up for a course, freelancing, vacationing, visiting, shopping, anything. Readers fall in love with compelling characters and they are way more fun to write. See the loop there? A novel in which characters are clearly outlined as "good" and "bad" like Smurfs vs. Gargamels, and have all the "right" and "wrong" views respectively, well, I've already fallen asleep writing this, zzzzzzz.
3.Avoid what I call laundry listing. As a manuscript editor, I see this often. It goes something like this: and then there was the time, and that time, and a decade ago. Writers present a keen point but expand until the point is closer to a grenade, exploding all over the page. You don't have to dig your incisors into your readers' necks. One popping anecdote is enough. Promise.
4.Location isn't just for restaurants. This is my personal pet peeve. I admit it. I've written about this before. Characters derive from their location and NOT the other way around. Sorry. This is where I need to duck because so many of you are throwing verbal paper airplanes at me. I know many writers say they begin with characters and there's nothing wrong with that but characters speak, act, dress, eat, think differently depending on where they are from and the time period, including the politics and the weather. Not budging from this one. No characters from, "Oh, it could be any modern city and any time after the 90s, winter, summer, election year, whatever." In how many languages can I write: don't do that? Pin down your location and time period as sharply as you can.
5.The paradox of criticism must be internalized. You must be open to criticism. It's not you being critiqued, it's the manuscript. But, hey, it's YOUR book. Respecting other people's points of view does not mean relinquishing your point of view. It's a hard task to keep that balance and walk it but if you don't, you risk blending into the crowd, writing a novel by committee, and losing your voice. No one will raise their hand for that role.