I'm aware that the fighting style of Greek hoplites was referred to as Hoplomachia (sp?) and that very few ancient Greeks actually trained or drilled in combat skills.
What I'm looking for are the best sources that we have on individual combat, dating as far back as practical. What are the earliest sources on individual fighting styles, whatever those may be? (Hoplomachia included, if there is such a resource.)
I'm working on a book about a wandering warrior, and I've asked a few questions in this sub before. It's... incredible the resources here. I'm learning that much of what I pictured of classical armies, formations, and battles was not accurate.
This leads to my current struggle: In order to properly write about what this warrior would be like, I need to understand what sorts of skills she would likely have. My book is fictional, so I can import training and skills that develop "late" in the real world back as far as I need to in hers, but I still don't really understand what those skills would look like.
No such textbooks exist. Nothing is known about the particulars of hoplomachia. This is no exaggeration; modern scholars continue to argue even over such basic details as the way the shield was held, and whether the spear was used for overhand or underhand thrusting, because there is no ancient source giving us unambiguous evidence one way or the other.
The particular reason why there are no surviving manuals or textbooks on the subject is probably that hoplite fighting skill was not considered important. You may already have seen the post I wrote about this here. Plato is the only Greek author to advocate a regular programme of hoplomachia for hoplites, and even in the context where he does so, he gives us no more than the word itself. In the Constitution of the Athenians (42.3), Aristotle's student tells us that the mandatory ephebeia of the 330s BC included training with multiple weapons, including hoplite gear - but again we find only the verb hoplomachein (fighting in armour), and no description of what it entailed.
The Roman legionary is the earliest warrior whose specific way of using his weapons is described in a literary source. For earlier warriors, we rely on iconography (with all the problems that their interpretation brings) and brief comments and anecdotes scattered through the sources. There is not enough for us to determine what would make a well-trained hoplite different from an ordinary one.
Sorry I can't do more to help you with your heroine. On the plus side, there should be no reason to object when you make your fantasy warrior do pretty much whatever you like...
Unfortunately, technical sources about personal combat are vanishingly rare before the fifteenth century. In fact, we only have two sources. One is Ms I.33, a book on sword and buckler combat kept in Leeds armouries and dated to around 1320. This is normally considered the first fechtbuch, but it's not quite the absolute first.
That honour belongs to [MS P.Oxy.III.466](http://wiktenauer.com/wiki/Oxyrhynchus_Papyrus_(MS_P.Oxy.III.466)). This is a fragment of a second century wrestling manual, describing a few throws and counters. It's extremely minimal, but there is just about enough material here for fighters familiar with wrestling to experiment with reconstructing it.
Beyond that extremely minimal source, however, we're entirely in the realm of speculation. And it's worth bearing in mind that this is still hundreds of years after what you're likely to be referring to as hoplites.