I've been hunting for a while for a way to do cuts. So far...not good options. I want to do a proper CUT, which doesn't show the stuff anywhere but on the page for the post itself. This is great for, say, cutting bits for the feed to chunk a post nicely. WTB lj-cut text="This should be simple"
Apparently, not so much. This looks like the most straightforward manner (and, don't try to use Blogger's official help as it's completely hopeless and incomprehensible). But, this does 2 things. 1) if you can find the body tag (which, I can't), and add the second bit, every single post will have the "read more" link, regardless of whether it's got a cut or not (if not, you need to manually add a link to the post before the cut to take people to the page with the rest of it). 2) And in my mind, the thing that makes it useless, all it's doing is having you drop the stuff you want cut in a span that it hides. Which means...it's still there. All of it. Just invisible only on your page o' posts because that's the only place the stylesheet turns it off. Feedreaders completely ignore the cuts, and show the full text, because they haven't been told to ignore it with css.
Wordpress appears to have a _real_ way to do cuts, I'm pretty disappointed blogger doesn't even consider the possibility.