Start with the great book by Prof. Joseph Naveh -- Early History of The Alphabet, Magnes Press; 1997 -- the Hebrew edition, out of print; 1982 -- English edition.
Whe I saw Raphael Freeman's profile picture, I was reminded of a question I've had for some time: Is there a good reference for historical Hebrew lettering—perhaps even the Aramaic alphabet? Is there another engraved inscription as old as the "place of trumpeting" stone from the Temple?
(I know the (Koren) [Yerushalmi] font is based on these forms; I'm wondering where there are good primary sources.)
ETA: I just remembered that Koren is based on the letterforms in the Aleppo Codex; my question has been corrected.
EATA: Also I found the Uzziah Tablet online. Are there other good examples? I'm sort of looking for the equivalent to Trajan's column.