How Much Is Too Much?

Twitter doesn't work if you only make promotional tweets.

I tweet far more than five or six times a day and have a lot of fun there, and a reasonable number of followers.

Don't think of it as a promotional thing. Engage in discussions there, make friends, and have fun. If you sell books as a result, that'll be great. And it'll be far more effective than having a sales-only twitter account.

I immediately unfollow anyone who keeps up a constant stream of advertisement. Or actually, anyone that tweets ANYTHING repeatedly. I followed one author I really love, but all she did was tweet about her dog, over and over. It was disappointing because I really wanted to hear updates about her writing, so eventually I unfollowed her (I don't want to hear that your dog barfed in the back-seat, really. I don't.) But as long as you mix fun tweets and interacting with other people, you should be totally fine to stick something about your book in there. I would say four personal tweets for every advertisement.

I don't partake in those awful 'buy my book' tweets but I do link to things that are going on with my book, like my blog tour, updates on my website etc and people do click into them, so it that respect I think it works.

As long as you use it like a human being and not a spam bot it should be fine.

OP, you're doing better than me! I might tweet twice a month or so. So yeah, I still haven't conquered the Twittersphere. I have an account, I have followers (some pretty well known authors at that), but I have yet to fully invest myself. I'm still married to Facebook, although there are indications that it is dying.

I just forget to post anything. When I do remember, I try to post my latest blog posts and any pertinent info on the book being for sale (no overbearing sales pitches...just "hey, the book is available here" or "the book got a new review and you can read it here". Perhaps I would tweet more if I installed it on my smartphone. I might try that out and see what happens.