Read the copyright page first. Look for "First Edition," a complete number line (must include 1), or a date/gutter code. Any of these tells you the printing.
Check the jacket price. An unclipped price is expected on a true first. SFBC copies have no price on the flap — that's the fastest tell of a book-club edition.
Magician 1982 — The cover shows a red-robed mage with swirling dragons (David Gatti). If you see a man in blue robes with a Midkemia city (Don Maitz), you're holding the 1992 APE. Both are desirable but very different values.
Silverthorn and Sethanon US firsts — Both have Kinuko Y. Craft covers. The Maitz covers everyone associates with these titles first appeared on 1992 reissues.
Daughter of the Empire US first — Cover was painted by co-author Janny Wurts (NOT Don Maitz). Maitz appears only on later printings. Know the cover.
Serpentwar US firsts — Rage and Shards both published by Avon, not Morrow. True firsts carry the QPM printer code on the copyright page. Missing QPM = later printing.
Rise of a Merchant Prince — The only Serpentwar book where the UK first (Geoff Taylor cover, Oct 1995) precedes the US (Daniel Horne cover, Nov 1995).
Legends trilogy (3 books) — UK hardcovers are the true global firsts for all three. US editions were trade paperback only. Any US "hardcover" is a book-club copy.
Krondor: The Betrayal — US first ships with an unopened CD-ROM (Betrayal at Krondor game). Missing or opened disc sharply reduces collectibility.
Tear of the Gods — Copyright page says (c)2000 but US publication was March 2001. True first = UK Voyager Nov 2000. Don't be fooled by the copyright date.
A Crown Imperilled — True UK first printing has NO jewel mark on the interior front flap. Corrected copies added the jewel. Also: UK title double-L (Imperilled), US single-L (Imperiled).
Geoff Taylor vs. Martin McKenna — Taylor painted virtually all HarperCollins/Grafton UK covers 1984 onward. But the Conclave of Shadows UK books 1-2 (Talon, King of Foxes) use Martin McKenna art, not Taylor.
Number line rule: The numeral 1 must appear in the number line for a true first printing. Any line starting 2 or 3 is a second or later printing of the same edition.
Price your expectations: Even signed true firsts are unlikely to fetch more than 5-10x the original cover price unless in fine/fine condition. Dealers typically pay 20% or less (Feist himself says he'd value his own signed copy "not a dime").