Share 'Could someone explain virtual book tours?'

I've heard this expression quite a bit, and yes I've seen many articles on the web talking about them. I've read things like guest blogging, interviews, podcasts, ect are all ways to be in a VBT. But out of all the articles I've seen, I still don't know how to set these things up. It also seems that if you talk about your book in writing groups, they say you're spamming. So how does one get atte…