Know Your Enemy
Are they short or tall? Their height will determine their stride length (helping you maintain distance), their reach (ditto) and your likely attack range.
Are they athletic? This will determine whether they get stronger or weaker as a fight progresses and how well you exhaust them by using your footwork and the length of the piste. It also gives you a clue as to your energy conservation strategy which could be vital in a 15 hit match
Are they experienced? Difficult to judge visually but after a few hits you should have an idea
What is their energy like? Are they calm, twitchy, nervous, prone to anger etc? This will give you a clue as to how to fashion your tactics
Are they left handed? Might sound obvious but this will definitely influence your strategy...!
Have you fenced them before and if so, do they have any favourite techniques? This will give you an idea of what to use against them
All these things will influence the way you choose to approach the combat and there may be other indicators that you will wish to develop for yourself. I would strongly recommend that you give it some thought though because it's too late when you've just lost.
* I originally typoed this as 'otter place of combat' - presumably for gladi-otters.... I thenk yew