They don't have to be witty bits of perfection. But you know. Something vaguely interesting would be nice.
If they are @ replies that seem to be in dialogue with someone, I approve. I may even click over to see more than your last three tweets. But mostly, at that point, I think, "Wow, an actual conversation! This may be a person worth knowing, for they understand that we are not all book-buying machines on Twitter!" And I probably follow you back.
If your last 3 tweets are pleas to buy your book, it's over before it has begun. You are abusing Twitter.
If you DM me to thank me for following you, and also, check out your book? It's over.
If you @ me to thank you for following you, and also, check out your book? It's over.
You can't thank someone and try to sell them something in the same interaction, and expect a fruitful relationship thereafter.
If you follow me, and I follow you back, and you act like I followed you randomly in your thanking? I know you aren't actually paying attention, and I unfollow again. Because you're just trying to use me.
You have absolutely no idea how to use Twitter, my friend. I want a hundred good tweets before you self-promo me. MINIMUM.
Or at least three.