What is your approach to series?

[NeverBeenWise]

If I don't know the series at all, I'll buy the first book, regardless of whether or not the entire series has been released. After I finish it I'll usually know what I'm going to do: if it was awful I won't read any more of the series, if it was decent I'll wait until the rest of the series comes out and buy one at a time, and if it was absolutely excellent I'll buy as many as I can afford/get my hands on. This approach has worked well for me in the past, because a lot of the series I read (Redwall, Xanth, etc.) don't have a specific number of books in them - they'll just keep coming out until the author gets bored. These, however, do not have to be read in any particular order, so I just started with whatever one looked the most interesting at the time.

If I already know the author's writing style and like it enough, like that of our beloved Robin Hobb, I'll buy trilogies at a time if I can manage it. But if all the books aren't out yet I'll gladly read what I can and then wait (im)patiently for the next installment, and read something else in the interim.

I have a funny little habit of reading three or four books at the same time, but usually all but one of them are re-reads, just so I don't get confused. Or they're completely different genres. I have another habit that's a bit more annoying: after I read a series, if it's really good, sometimes I'll set it aside for a couple of days... and then proceed to read it again. For example, a week after I finished Fool's Fate I started again on Fool's Errand so I could get every little detail. And usually if I know I didn't read the entire series in order, once I've finished everything I'll go back to the beginning and read every book from start to finish. Once I couldn't even wait a couple of days; I closed the book, stared at it, and promptly started to read it again. I don't know why. Does anyone else do this?