What sorts of “things”? As you’ve noticed, the more tag shows your entire post up to the tag.
There are some other options, but would be good to hear a bit more about what your goals are.
I want whats before the more tag to display on the main page, but not when the entire post is viewed?
Hrmm. That should be kinda how it works now.
By default, when you click the “more” from the main page, you are positioned to what follows the “more” on the single post view. Which would, in theory, essentially do what you’re asking. Yeah, the other stuff is still there but it’s scrolled up and out of the way.
Well, it will only be scrolled up and out of the way if the post is long enough for that. If it is a short post then the entire post will show… don’t think there’s much you can do there.
So here’s another way you could do what you’re asking. In your theme’s index.php, change the_content() to the_excerpt(). When you write your post, put what you want to see on the main page in the Excerpt field on the write post page. Put the rest of the post in the regular write post field.