I seem to have gone slightly meta, in that I'm writing a blog about my blog, but this is the sort of thing I want to document since I don't want to forget what I've done, in case I accidentally update a template and forget to merge this change back in.
You'll notice some of the long posts here will now get just a summary, followed by "Read More...", which is your indication to click:
I know I'm a long-winded chap, so I wanted to start breaking up the posts into pieces.
After a lot of searching and experimenting, I've gotten it working. I'm using the help provided by the blog Pinkish, but I found an error in their instructions which added a lot of time.
Without duplicating the entire content of the post, I'll point out Step 4 and Step 5 say:
Your splitted posts should look like:
This is part one of my post
This is part two.
But the correct span tag is <span id="fullpost">. This is critical.