I'm in year three of my PhD. I've written... I don't know... 15 research papers? 20? Here's what I wish someone had told me at the beginning. 
One: Your first research question will be too big. It always is. You want to solve world hunger. You want to revolutionize your field. Scale down. Ask a smaller question. Answer it well. You can scale up later.
Two: Stop reading and start writing. I spent my entire first year "preparing" to write. Reading more. Taking more notes. Organizing more files. I was procrastinating. Writing is scary. Reading is safe. But you can't read your way to a finished paper. At some point, you have to write something bad so you can revise it into something good.
Three: Your first draft is allowed to be terrible. I used to try to write perfect sentences from the beginning. That's insane. That's like trying to bake a cake by putting the icing on first. Write garbage. Then fix it. That's the process.
Four: Feedback is a gift. I used to dread getting comments on my papers. I saw feedback as criticism. Now I see it as free labor. Someone read my work and told me how to make it better. That's amazing. That's a gift. Say thank you.
Five: Done is better than perfect. I've never submitted a paper that I thought was perfect. Never. There's always something I wish I'd done differently. But at some point, you have to let it go. Submit it. Move on to the next project.
Six: Take breaks. I thought working 12 hours a day would make me more productive. It didn't. It made me burnt out. Now I work in focused chunks. I take walks. I sleep. My writing is better. And I'm less miserable.
Seven: Find your people. Grad school is lonely. Research is lonely. Find a writing group. Find friends who understand. You can't do this alone.
One: Your first research question will be too big. It always is. You want to solve world hunger. You want to revolutionize your field. Scale down. Ask a smaller question. Answer it well. You can scale up later.
Two: Stop reading and start writing. I spent my entire first year "preparing" to write. Reading more. Taking more notes. Organizing more files. I was procrastinating. Writing is scary. Reading is safe. But you can't read your way to a finished paper. At some point, you have to write something bad so you can revise it into something good.
Three: Your first draft is allowed to be terrible. I used to try to write perfect sentences from the beginning. That's insane. That's like trying to bake a cake by putting the icing on first. Write garbage. Then fix it. That's the process.
Four: Feedback is a gift. I used to dread getting comments on my papers. I saw feedback as criticism. Now I see it as free labor. Someone read my work and told me how to make it better. That's amazing. That's a gift. Say thank you.
Five: Done is better than perfect. I've never submitted a paper that I thought was perfect. Never. There's always something I wish I'd done differently. But at some point, you have to let it go. Submit it. Move on to the next project.
Six: Take breaks. I thought working 12 hours a day would make me more productive. It didn't. It made me burnt out. Now I work in focused chunks. I take walks. I sleep. My writing is better. And I'm less miserable.
Seven: Find your people. Grad school is lonely. Research is lonely. Find a writing group. Find friends who understand. You can't do this alone.