How can I tell if my book is a first edition or not?

There are several ways to see what edition your book is. First of all some of them actually have "First edition" printed on the copyright-page but some has these strange figures, like:

1 3 5 7 9 8 6 4 2  or  1 2 3 4 5 6 7 8 9

which both means that it's a first edition - you always go by the first figure. In other words

4 6 8 2 3 1 7 5

is a fourth edition.
But some of course neither has the words "First edition" nor the figures. In that case it can be a little bit trickier to find out what edition it is. There's a good guide to this located on the SKEMERs website.

Bookclub editions can be identified in several ways as well. Sometimes is says "Bookclub edition" somewhere on the book, sometimes the dust jacket doesn't have a price and sometimes there's a little dot on the backside of the book.

I hope this gives you a little help...