There's nothing I wish I'd known before I started, mostly because I still don't know a great deal. There are some things I'd really like to know, though. Like:
1. Why sometimes you can write something good (modest as ever) which gets ignored, and then something really silly and ranty gets loads of attention.
2. How some people (you know who you are) post 900 times a year and still appear to lead an external life of some description.
3. Why one post that I wrote last year has had more hits than any other, by a factor of 5.
4. Why there is isn't a simple ranking site that ranks blogs by the most obvious criterion of quality - how many people read them.
5. Why backlinks don't work on blogger.
6. Why more clergy, especially those in public roles like Bishops, don't blog. Or, to put it another way, why we don't choose more who can.