As a writer, you are your brand. Every few months, you need to look at your social media presence and make sure that it's polished.
1. Make sure your name is consistent across your sites. If you use pen names, be sure to have a place where you note the other names you use. People need to be able to identify you. It gets confusing if you use different forms of the name (e.g. Tom, Thomas, Tommy, T).
2. Your picture should be similar or the same on your sites. Readers need to be able to recognize that it's you. (I do have different pictures on my personal and author Facebook accounts. It makes it easier to tell which account I'm using to post.) Update your photos every year or two.
3. Your color schemes and artwork should be similar. You need a theme that appears on all of your sites.
4. Check the blurbs that describe you on each site. They should be consistent. Don't overwhelm them with hashtags. Make sure to include your latest book. Update these every few months.
5. Update your email auto-signature to include your social media and web links.
6. Update your content frequently. People don't return to sites where the content never changes. Remove all outdated information. Nobody wants to see a list of your book signings from 2013.
7. Follow the 80/20 rule for content. Eighty percent of your author content should be informational, fun, and conversational. The goal is to build relationships. Only about twenty percent of your content should be "buy my book." Readers tune out noise after a while.
8. When followers comment, retweet, post, or share your content, make sure that you notice and thank them.
9. Check all links on your sites to make sure they're working. If you have a "contact me" section, make sure it works too. You don't want to miss something because of a broken link.
10. Mix up your content. If people follow you on several sites, they don't want to see the same post four times.