You'll start with Gary Forsythe, A Critical History of Early Rome. From Prehistory to the First Punic War (Berkeley: UC Press, 2005), and you'll have next to you for reference The Peoples of Ancient Italy, eds. G. Farney and G. Bradley (de Gruyter 2018). You'll have a solid translation of Livy next to you as well, or, even better, the Latin text with Ogilvie's commentary.

When you are done there, and after you have combed through the vast bibliographies of those two monographs, you'll be ready to move on to the Middle Republic / Punic Wars. Again, you'll want an authoritative monograph with good notes and good bibliography. A great place to start hunting for it will be one of the "Companion" series books, like A Companion to the Punic Wars ed. Hoyos (Blackwell 2011). They are great at giving those new to the subject a good overview. From there, you can excavate that bibliography and find the good books on the topic, which will invariably be from Oxford, Cambridge, Leiden, de Gruyter, Blackwell, or one of the major American presses like Princeton, Chicago, UC, Yale, Cornell, etc.