If you do not specialize you can get overloaded with items and information. As with 
any
collection there are several things to learn and to take into consideration when
purchasing
books. I don't know everything and below are only a few of the things I do consider, or
 watch for when I am purchasing books. Remember that I have only highlighted a small part
  of the subject.
I try to collect first editions, out of print, and/or limited editions. It is not always so easy
 
to recognize a true first edition. On occasion, if a book is extremely scarce I
will purchase
 
a 2nd edition in hopes of one day obtaining the first edition. Books can be
repaired 
and/or
  
rebound, and that is another subject not discussed here, but that is also expensive. You need
 
to take into consideration the value of the book after it is repaired. 
This may be the thing to
  do if the book is real scarce and not much other options of getting one.
Many books come in sets, often only 3 or 4 books to the set.  If at all possible try to
obtain
 the complete set. I have several, but one I am especially proud of is my set of silhouettes.
I have all 27 books in this set. It is good to familarize yourself with the publishers, ones
such as University of Arizona Press
 which has published a lot of Arizona material. I rarely
 
read fiction but one exception was Louis L'Amour's
 "Flint". I enjoyed it immensely.
I\We have found many new sources of information on the internet since Mary took the 
 Glendale Community
College
CIS133 Internet class. The Internet has almost anything someone would want to
find.