Truly, you have a great ambition. Don't give up!!
But you cannot learn to talk an ancient language just from the way it is written. Heck, you cannot learn how any language is spoken from the way it is written, though maybe Korean comes as close as any.
That aside, decipherment of ancient scripts is very worthy. But to decipher a new ancient language needs a huge amount of ability in languages, knowledge and frankly probably a lot of "luck" as well. (How about just learning to read a language that has already been deciphered? There is a tremendous need for readers of the different languages written in cuneiform.)
For personal suitability, you need to ask are you generally good at languages, are you fluent in more than one language? Do you have a flair for puzzles, especially linguistic puzzles? Are you willing to spend many years struggling over a conundrum?
(I dont' want to put you off entirely, but have you read the first few sentences of the wikipedia for Jean-François Champollion? Not all decipherers were quite so brilliant.)
As for books, I recommend:-
"The Story of Writing" by Andrew Robinson (Thames & Hudson, London, 1995)
"Reading the Past - Ancient Writing from cuneiform to the Alphabet" with introduction by J.T. Hooker [authors: V.B.F. Walker (cuneiform); W.V. Davies (Egyptian Hieroglyphs); John Chadwick (Linear B); John F. Healey (The Early Alphabet); B.F. Cook (Greek Inscriptions); Larissa Bonfante (Etruscan)].
From Hooker's intro:- "The six books brought together in this volume explore in detail specific stages in the story of writing, with special emphasis on the decipherment of ancient scripts..."
If you cannot find where to buy it I got my copy of this and "The Story of Writing" from the British Museum, London (but that was quite a few years ago).
A very recent noble example of decipherment (without leaving your living room!) is:-
"The World's Oldest Alphabet - Hebrew as the language of Proto-Consonantal Script" by Douglas Petrovich (Carta Jerusalem, first published 2016) - but note Doug Petrovich has acclaimed expertise in multiple relevant fields ("epigraphy, palaeography, lexicography, and comparative linguistics and literature" from introduction by Eugene Merrill) (NB This book will set you back 50 british sterling.)
Finally, for what its worth, "New Tribes Mission" and "Wycliffe Bible Translators" both specialise in teaching Christian students how to learn a new tribal language (which no one outside the tribe knows and has no written form) and how to produce the written form, together with a written grammar and dictionary (eg an English/new language dictionary), and then how to write the Bible in the new script; and then how to teach the tribe to read. (I guess some anthropologists must hate them.) If you are interested in that then the biography "In Search of the Source" (by Neil Anderson with Hyatt Moore) gives a beautifully written example of the outworking of such training.
Best regards, Andrew