1. Read their work. But like, really read it, though. Soak it up. Tell them what you liked about it. Tell them how it made you feel. Marvel at their clever word choices and melodious phrasing. If you haven’t had time to read their latest piece yet, say, “I’ve been saving it for when I can really take my time with it,” and mean that, and follow through.
2. Brag about them. When the subject of her last piece comes up at a dinner party, inquire, “Did you read her article about that? It was great!” When you introduce him to your friends, tell them, “He’s an incredibly talented writer.” Have her big-deal byline framed. Bring up his accomplishments in spaces where he might be too shy to do so himself. Be your sweetheart’s one-person hype machine.
3. Read their work aloud to them. Whether it’s an in-progress draft or an essay they wrote years ago, they’ll hear it differently in your voice. They’ll adore hearing which sentences surprise you, which metaphors make you giggle, which piece of dialogue trips you up. It’s a sort of artistic collaboration: their words, your voice, mingling to create something new.
4. Don’t offer edits unless asked to. If you’re not sure, ask before you begin to read, “What kind of feedback are you looking for on this, if any?” Sometimes they might want your detailed suggestions. Other times they might just want someone to look it over and say, “This is great!”
5. Nerd out about books with them. Be the person to whom they can text excerpts excitedly, or shriek gleefully about perfect sentences. Recommend them your favorites, and read theirs. Lie in bed together reading, taking occasional breaks to query, “What the fuck is this character doing?!” or “How the fuck is this going to end?!” Give them a gift certificate to their favorite used bookstore, or an annotated edition of their fave novel, or a shiny new Kindle. Hold them and kiss their shoulders while they devour something beautiful.
6. Let them bounce ideas off you. Help them shape the plot of their novel, or the arc of their essay, by listening and asking questions. Tell them what’s working for you and (gently) what isn’t. Point out plot holes or fallacies, and help them fill in the gaps. Develop the skill of being diplomatic but honest when asked, “Does this make sense?” or “Is this funny?” or “Is this any good?”
7. Write them love notes. Their love language is probably linguistic, so they’ll appreciate this even more than the average person. Put into words why you love them, what they mean to you, what they bring to your life. Tell them how their presence in your life heals your past, sweetens your present, and brightens your future. Write things that are meaningful, sweet, and true. Your prose doesn’t have to be flowery or crystalline like theirs is, though maybe they inspire you to make it moreso.
8. Surprise them with beautiful writing supplies. But ideally the ones you know they prefer, since that proves you truly know them. Get them their next journal, a box of exquisite pens or pencils, a year-long subscription to Evernote Premium or a domain for their blog… Whatever you know will get them fired up to write even more.
9. Give them space to write. Don’t take “I can’t; I’m writing” as a rejection; be flattered they trust you enough to be honest with you about their boundaries and needs. Don’t interrupt them when they’ve retired to a private space to write – or, if you must, ask first if it’s okay. Find ways to work on solitary pursuits, independently but together – they will feel adored and accepted when they see you can amuse yourself with some other activity while they write, happy just to be near them. They’ll be happy to be near you, too.
10. Give them things to write about. Magical experiences, poignant moments, deep and true love. Kiss them in pretty places, hold their hand in bustling streets, shoot them meaningful glances from across a room. Incite in them joy and lust and exhilaration and whatever feelings you’d want to read about – because they want to write about those feelings, but more than that, they want to feel them.
Phone sex. I HAVE A LOT OF FEELINGS ABOUT PHONE SEX. Eventually I will write some kind of how-to, although I don’t think I’m very good at it. (Suz is, though, and she wrote 
The first time I fell in love, I was nineteen, and I knew because I simply wanted to say it. It felt natural. The same way I might tell a close friend I loved them, so too did I want to say it to my then-boyfriend. It wasn’t a sweeping passion or a roiling lust; it was a slow warmth that had gathered and grown over the two-plus months of our nascent sweet springtime romance. At first I wasn’t sure, and then at some point, I was. When I said it, in the dark in my twin-sized bed, he hugged me tight and said, “I love you too, and you’ve made me a very happy man.”
When my current beau first told me he might be falling in love – by invoking late-night Google searches and Wikipedia trawls – I wasn’t sure how I felt on that front. “I feel like I should have more to say about this,” I wrote after relaying the episode to my journal. “Do I want to fall in love again so soon after 
We finally say it on our third date. That sounds ridiculous, unless you know how many hours we spent on the phone between each in-person rendezvous. Long phone calls stretched four or six or eight hours into the night, entire emotional journeys of their own, with laughs and tears and phone sex and warm cuddly mumbles. We fast-tracked our relationship on those phone calls. We rushed toward love, exhilarating and good.