I think it mostly depends on when there are two equally good continuations, one more positional and one more tactical. Which do you prefer?
You could always try chess.com's personality quiz at chesspersonality.com.
But in any case, I really wouldn't worry about it too much. Just play good moves and try to improve where you're weak. Eventually you'll become more certain of whether you tend to be more positional or tactical.
Some advices about how to improve say that you first have to know whether you are a tactic or strategy player.
But how can I know? If I think a move is good I play it, whether it is positional or tactical. I don't think I have a preference.
And how can you tell if you are aggressive, defensive or balanced player?
Here is a few of my games.
http://www.chess.com/livechess/game?id=1378149862
http://www.chess.com/livechess/game?id=1377999210
http://www.chess.com/livechess/game?id=1377960380
http://www.chess.com/livechess/game?id=1377929331
http://www.chess.com/livechess/game?id=1377187403