I just read this blog and found 2 things I didn't know so I thought I'd share them here.
familysearch hints blog
Basically use the keyword search to find things, as you can get more results than a place search and make sure you are always logged in. Apparently familysearch will log you out without your knowledge.
My own hint for when looking at parish registers online - if you can't access the normal parish registers you can often access the BTs.