What is WorkFlowy? I crave simplicity online and don't add tools and services for the novelty of it. WorkFlowy does one thing very well - it allows me to create lists of things that I'm going to act on. Evernote is a tool I use to keep things that may require action and may be for reference. Like school calendars for my daughters. I take a picture of them and keep them in Evernote but then those notes clutter up my interface when I'm looking for something else.
WorkFlowy is clean, list making app. To start, I made different lists for different projects DC is my work list, Home is my home list, Blog is my blog list. Under each of these, at an indented level, I have more lists. There is the "Month of writing posts for WorkFlowy instead of evernote" and indented under that is specific post ideas. After that list of posts for there level pops back out and there are other things that will be blog posts.
This is not a repository of things - Evernote still serves that role - these are lists of actions to take. The specific blog post line items are things I'm actually going to write about. They may not be good posts and may not be published, but I'm still taking action on them. It's the same under Home, where if I expanded it, it would show that I need to clean out the gutters.
If you love making lists to get things done and this category/subcategory structure appeals to you then go check out WorkFlowy. They offer a free getting starting plan. They also have a great iOS app and web interface that the screenshot above is from.