What Should I Buy? recommendations from Kathryn Smiley

Kathryn Smiley, editor of "Firsts" magazine, was interviewed in the "Official Price Guide to Collecting Books" by Marie Tedford and Pat Goudey.
Her advice to a new collector is, first and foremost, collect what you love.  "Book collecting for investment is not a great idea.  We never advise anyone to get into book collecting with an eye to making a gazillion dollars, particularly modern books, because it's difficult to predict which ones will be popular down the line."
In general terms, collectible books hold their value well, and even steadily increase.  But they do not make good speculative investments, and they're not likely to make you a killing.