I'm just starting out studying Plato myself under a philosopher and he says it's no use trying to read Plato unless you have read A LOT of literature. This is the only way, he argues, that you will acquire the tools necessary for the study of philosophy. But you must read literature "the right way" -- you must re-experience what the author has experienced. This is much easier to accomplish reading literature than studying philosophy, for that is all literature is: the translation onto the page of what the author has experienced.

Philosophy is the same thing, but once removed. It can get abstract and you can get lost trying to find the thread back to the philosopher's originating experience. But philosophy has this in common with literature: it is also an experience. And the philosophical method entails re-experiencing what the philosopher has experienced. If you don't do this, it will be no use trying to "understand" -- perhaps that's not even the right word to be using. You must always concentrate on EXPERIENCE. I actually go around counting how many times an explanatory text on Plato uses that word. Although I haven't read it yet, the text you pointed out -- "Approaching Plato" -- uses that word more than twenty times. One of the lines seems very appropriate: "The Euthydemus is not a dialogue to study. It is an experience."

Sorry about maybe having too long a comment, but here is a quote from one of his lessons (which I translated from the original, in Portuguese):

"One book that I will indicate — don’t read it now, just keep this in your head — is the book on Plato by Paul Friedländer [Plato: an Introduction. New York: Harper and Row, 1958]. It’s a great book, which left its mark on three or four generations of Plato scholars. What is Friedländer's secret? He links ideas back to experience. He searches out the specific circumstances, concrete and human, in which certain questions occurred to Socrates and Plato, and shows how they interpreted and worked on their own experience to extract from them the philosophical concepts that they would later discuss. To discover the experiential (not “experimental”) substance of the philosophical concepts is practically everything. This is the philosophical method itself. It is an immense effort, not only in the intellectual sphere, but also in the psychological and moral spheres as well. Many times it will be necessary to search for the roots of philosophical concepts in internal experiences that you had twenty or thirty years before: it is an intense labor of anamnesis, of self-knowledge and self-analysis, and what spoils philosophy are the people who do not know how to do this. Because whoever doesn’t know how to do this uses philosophical concepts as fetishes, as if they were things in and of themselves, and they go into a verbalism without restraint in which they never know what they are talking about and never admit to being called upon to clarify. These people have fear: since they have no human substance nor experience of life, but only what they read in books, they never know what philosophers are talking about. They know what the philosopher said, but not to what that corresponds in reality, and therefore what they say has no substance in reality; it is only academic verbiage."