lots of good stuff here, sorry to be late back, but with 14month old twins, and an 8 year old added to the mix, life's kind of hectic here!
Can I ask about technology, do you ask to have their passwords for email, phone etc? Do you put parental controls on their ipads/laptops? We've never had this problem before as our computer is in out living room, until now I have always been here when they have been on, but now she has an ipad, which is surgically attached to her hip, and of course I cannot be sure what she does on there all the time, even though I am as sure as I can be, it's normally, music, youtube, chats to her friends, all quite innocous (sp?), as she is still quite naive, but of course this can change without warning...
I guess what I am trying to say, is I don't want to give her the impression I do not trust her, until and if, she proves me wrong. I don't like to start with "mistrust" as default iyswim?
But then she recently asked to open a tmblr account, of which I knew nothing, so I said I'd check it before saying yes or no. When I saw what it was I just queried why she wanted to do a blog, and one that cannot be kept private from what I understood, she couldn't explain why so we kind of left it at that. Now I think I've seen emails from tmblr in her email inbox relating to 'her' account, but not sure... so how do I approach this? it is hardly the crime of the century, but she was supposed to have waited, then again I am not 100% sure of what I have seen, so can't confront her on this.
I do not want to push her into doing things behind my back..
I guess there is no magic formula is there? I just want to keep lines of communication open, I was very troubled as a teenager, and if her toddler years are anything to go by, I will need that desperately.
bubby taht is so true about "secondary behaviour" and one I have definitely been guilty of 
I like this two tiredaftertwo
'Be available to them if they want to do things with you. Try to find things you all/some of you enjoy doing together in and out of the house, and find time for them. Encourage any sort of sport or outdoor activity before they reach the bedroom troll stage'
Thanks again all of you, it's given lots of food for thought. I am still most definitely NOT ready for this, and I am sure I will be back for more 