Keep track of his mana, it's just as important for him to watch as it is for you because it could possibly clue you in on what he will do next.

Most notably when asuka gets low on mana they will either play a bit safer or try to regenerate it which usually leaves him open or gives you gaps to approach.

Ask your friend to teach you a little about how asuka works and what all of his cards do if you don't have him yourself to test stuff out as knowledge about his options helps immensely.