I use Instagram to post WIPs, sketches, and cropped finish panels for every comic and novel update. Then I use an IFTTT recipe to automatically post them on Twitter as native Twitter images instead of just a link. All my tags and stuff are preserved, which is lovely.
I use the Instagram sharing settings to post them on my Facebook and Tumblr pages as well. Keep in mind that Facebook also preserves tags, but crossposting to Tumblr isn't too great because they don't make those posts searchable. If you really like using Tumblr and are active on there, you'll need to post from Tumblr.
For Patreon I post content and comic pages 2 weeks early, as well as more extensive WIP shots, since I am limited to 3 square images on Instagram (a row in your gallery is 3 images and I try to update 3 pictures at a time to have themed "stripes" in my gallery).
I try to do about one blog post a week on my homepage. Generally these are for art shows and events, but if nothing particularly is going on that week, I have a slot to promote a comic or the novel. I use wordpress's sharing settings to share these blog posts to my Facebook page, my LinkedIN, Google+, Twitter, and so on as the post dictates.
Lastly I try to remember to look up the best hashtags to use while I'm crafting a post. It does seem to get more eyes on your updates when you use popular tags.
As people above have said, the main rule is to GET OUT THERE FIRST, as soon as you have anything to share, and keep on sharing to gather people to you. You can refine your sharing approach as you go and change what doesn't work for you, but first you have to show them you're out there doing something.
