Augustine’s works can be found in all the major series (Migne, CSEL, CC, SC) and in very many translations.
For the Latin texts CSEL and CC and the obvious starting point.
The best bi-lingual edition is the Latin-French series Bibliothèque augustinienne. Each volume has substantive introductions and scholarly critical notes. This project was initiated after the last war to present Augustine’s work to the public in a modern translation, accompanied by the essential critical clarifications. Some of the earlier volumes were, however, poor in the scholastic mode; and this includes the text Lacan comments on at the end of S1.
Now each volume is preceded by a broad introduction which is generally a new study on the edited work: its dating, its literary genre, the historical, philosophical, theological or exegetical problems it poses. A copious infra-paginal annotation helps to understand the text, in particular by situating the themes treated in relation to the whole of Augustine’s work and by placing them within the framework of ancient thought; the additional notes, which take stock of difficult questions, often amount to small articles, which are cited as such in the specialized bibliography.
English translations of some of Augustine can be found online on a number of sites e.g. Early Church Fathers – Christian Classics Ethereal Library
Burnyeat, M. F. (1987). ‘Wittgenstein and Augustine De Magistro’ Proceedings of the Aristotelian Society, Supplementary Volumes 61: 1-24.
Brown, P. (2000). Augustine of Hippo. London: Faber and Faber.
Markus, R. A. (1957). St. Augustine on Signs Phronesis 2 (1): 60-83.
Marrou, H.-I. (1938). Saint Augustin et la fin de la culture antique. Paris: E. de Boccard.
Rist, R. A. (1969). Augustine on Free Will and Predestination Journal of Theological Studies n.s. 20: 420-47.
O’Connell, R. J. (1964). The Riddle of Augustine’s ‘Confessions’: A Plotinian Key International Philosophical Quarterly IV:.327-72.