How Much Should You Be Investing in Your Books?

I generally, at this point, as a fairly prolific author, do more effort into book one of a new series. But i will say, too, joe's comment on the amazon thing, the they seem to be kind of erratic whether they send out something or not. It does come it is triggered, i believe, just by the follow because i have some authors that, you know how you stalk people from time to time as tey're doing well in your jonor? You want to see what's going on there. I've seen successful authors say they spend 500 thousand a year to make a million dollars a year, and i've seen authors say they don't