When I was younger, I thought writers worked in really cool places, wrote great books, and got lots of royalty checks. I had no idea about what it was really like -- writing, publishing, networking, and marketing. Here are some things I've learned along the way.
Blog/Website - You need to have a professional Internet presence. If you can't build and maintain it yourself, hire someone to help. If you do hire someone, make sure you can keep the content fresh. People don't return to your site if the content never changes. A blog (on your website) is a great way to have new content regularly. Decide what blogging schedule works with your writing life and commit to that. I used to blog three days a week, but it became too time-consuming. I post once every Friday now.
Social Media Presence - Time spent on social media sites can get out of control quickly. There are so many out there, and it takes time to develop relationships and followings on each of them. Figure out what works for you and your readers and focus your time on those. My primary social media sites are Facebook and Twitter. Previously, I used LinkedIn for my IT life, but I do promote my blog posts there now. I like Pinterest, so I hang out there for fun. I have a presence on Pinterest, Google+, Tumblr, LinkedIn, Instagram, Twitter, Facebook, Goodreads, Amazon, and BookBub.
Professional Photo - If you're going to invest in something for your writing career, get a good headshot that you can use for your branding. Put your photo on your website, blog, and social media sites. And if you haven't updated your photo in the last ten years, it's time.
Press Kit - Put together a press kit (photo, short and long biography, book list) and make it accessible on your website. Have two to three biographies of different lengths. When you're asked to do events, the hosts want this information. Make sure that you keep your biography current.
Press Releases and Blurbs - For me, these are harder to write than the book. If it's not your strength, find help or resources on the Internet. You will need these. And it's better to have them written and ready.
Public Speaking - I enjoy panels, workshops, and interviews, but I've been a teacher, trainer, and Toastmaster through the years. I was surprised at the amount of public speaking that I'm asked to do. If you're shy or don't like to speak in front of groups, you may want to try Toastmasters. It's a friendly environment to practice in with constructive feedback. Many libraries and book groups ask for speakers.
Time Management - There is a lot involved in the writing life. I'm in two writers groups and two critique groups. I work, blog, write, volunteer, and do family stuff. Sometimes, it's a challenge to balance everything. Watch your time. Make sure that you make time for writing and revising. Book marketing and social media can take up a lot of your resources.