Don't put code before your text in blogs

I just realised that all the code I put in these entries shows in blog text previews if I write it before the text itself. No wonder no one was reading my blog entries since all they see is a bunch of random code. I don't know if anyone else has done this mistake, but I thought I would share it. I wonder if it's possible to hide it entirely from the preview, if anyone knows about that, please let me know.