This post arises out of something I wrote for first year MA in Classical Studies students at the Open University, but it also draws upon my experience teaching for the MRes in Classical Research at Roehampton.
OU students have an amount of independent reading time, and I suggested that a good idea for at least part of that was to work their way through various chapters of David Schaps' Handbook for Classical Research, which is a set book for the OU module, recommended for Roehampton, and pretty useful for anyone. Few Masters' students will need to read all of this, but I think it would be very good to make sure that they've read Part 1, which covers 'The Basics', and at least study the table of contents for the rest, so that they know what chapter(s) to come back to once they've finalized what they're going to be studying in depth. (With caution - some chapters of Schaps are better than others; archaeologist colleagues are not impressed with what he says about archaeology.)
I do think that it is important to consider overtly one's theoretical approaches and methodologies. Everyone has them. Even those people who are suspicious of theory and advocate its rejection (such as the late David West, in his notorious 1995 Presidential Address to the Classical Association, 'Cast Out Theory', which I was there to see) are actually adopting a theoretical position. It's impossible not to. This doesn't mean that it is necessary to commit oneself to any one rigid approach - my own approach, which mostly draws on new historicism salted with some insights from post-modernism (see Schaps, 2008, pp. 123-24), very much aims to be theory-aware without being dogmatic (for further expansion of my views on theory, see this blog post).
I also think (and this is a point I used to hammer home to Roehampton students) that it's very important to read outside Classical Studies. Traditionally, Classicists have been quite insular in this regard, wrongly so, I would argue. It is particularly obviously wrong when applying theories that have come from elsewhere. One cannot reasonably take a feminist approach to Classical material solely on the back of Nancy Sorkin Rabinowitz's introduction to Feminist Theory and the Classics, brilliant though that is (you can read all but one page of it on Amazon). It is necessary (and I think most feminist scholars would agree with this) to go and read some mainstream feminist theory, from the likes of Simone de Beauvoir or Germaine Greer or others.
But this doesn't just apply in such obvious theoretical areas - it also applies in fields that seem much more mainstream in Classical Studies, such as ancient history or archaeology. It was certainly the case when I was a postgraduate student that it was far too easy for an ancient historians to be produced who had never read a word of the historiographic theory of E.H. Carr, Eric Hobsbawm, Arthur Marwick or Arnold Toynbee* - a big regret of my postgrad career is that, being in a History department, I didn't ask to sit in on the department's module on The Study of History). One of the reasons I admire Neville Morley is that ever since Writing Ancient History in 1999 he's been arguing for ancient history being informed by historical theory - but I'm not sure how much his ideas have taken hold (and if your only engagement with historical theory is to read Morley, well, you're doing it better, but you're still not doing it right). There are probably significantly more Classical archaeologists who have dipped into the likes of Renfrew and Bahn's Archaeology: Theories, Methods and Practice, particularly at post-graduate level, but the point still needs making.
This is not something that Master's students necessarily need to think about right at the beginning of their studies, but it is something they need to address when they are thinking more overtly about their dissertation. And as often with these things, the earlier the start, the better it will be.
Keen, T. (2009) 'Reception Theory: Some Preliminary Thoughts', Memorabilia Antonina, 4 January [Online]. Available at tonykeen.blogspot.co.uk/2009/01/reception-theory-some-preliminary.html (Accessed 27 October 2016).Morley, N. (1999) Writing Ancient History, Ithaca, NY, Cornell University Press.
Rabinowitz, N.S. (1993) 'Introduction', in Rabinowitz, N. and Richlin, A. (eds) Feminist Theory and the Classics, New York & London, Routledge, pp. 1-20.
Renfrew, C. and Bahn, P. (2016) Archaeology: Theory, Methods and Practice, 7th edn, London, Thames & Hudson.
Schaps, D.M. (2008) Handbook for Classical Research, London & New York, Routledge.
West, D. (1995) Cast Out Theory: Horace Odes 1.4. and 4.7, London, The Classical Association.*In the past, when I've made this point, I have sometimes had responses along the lines of 'I don't really like Carr/Hobsbawm/Marwick/Toynbee', which is missing the point. I have no issue with someone finding some other historiographic theorist to draw upon - the point is that there's a lot of theory out there, and ancient historians certainly weren't, and possibly still aren't, reading enough of it.,>
What I omitted from this was a recommendation for OUP's Very Short Introduction series as good initial ways in to various aspects of theory.