The next question was: did it make a difference to sales? Again, we all agreed that it wasn't about sales so much as raising one's profile in the industry, which led to journalistic commissions and offers to speak at libraries and lit fests.
And another thing we all agreed on (it was a very harmonious lunch) was that obvious self-promotion was a turn off. We simply stopped following anyone who appeared pushy. One of us - not me BTW - had a problem with a friend of a friend who was emailing to ask her to re-tweet his posts of self-promotion. Unfollow, we all advised.
All of us had gone further and taken against authors who relentlessly promoted their books. We'd also made judgements about who we liked or didn't like on the basis of their on-line media presence. It may sound crass to base your reading choices on the personality of an author, but we'd all done it. I had been going to buy one particular novel, and then decided against it because the author seemed such an opinionated, judgmental person on-line. Maybe they are, maybe they aren't, but their media presence made me not buy.
As an author myself, this makes me slightly uneasy - just because someone promotes themselves well, it doesn't follow that their book will be a good read. But hey, aren't all purchases based on flimsy things like a good blurb, or personal quirks of preference. I once did a first page exercise in class using the Booker Prize short-list where several students rejected one particular book because a sailing ship was mentioned in the first paragraph and they didn't like books about the sea.
Back to the lunch. Our advice can be summarised:
1. Engage with others, and don't just be Me! Me! Me! all the time.
2. Don't expect to see direct results in terms of sales.
3. It can eat time, so you need to set up strategies to make sure it doesn't.
4. You don't have to do everything; I don't 'get' Facebook, but love Twitter, it was the opposite for one of the other writers.
5. If you're writing for children, you may have to be inventive about how they follow you - there are age restrictions on some social media networks.
6. Don't do anything you don't like, but on the other hand, don't dismiss it immediately - it takes time to settle in.
7. If you blog, update it at least once a week or don't bother at all.
8. Group blogs, where you blog once a month, are useful if you don't have much free time (or much you want to say - not my problem, ahem).
9. On Twitter, get to grips with various areas like mentions, hashtags etc. I didn't realise about the mention facility at first, and spent hours scrolling through in case I'd missed someone talking to me.
10. Have fun!