how do marley's actions suggest that he can be mischievous

One indication of Marley's mischievous spirt is that Scrooge's first sighting of Marley's ghost comes when Marley shows his face in the door knocker, with his spectacles pushed up on his head. Scrooge then thinks he sees a "locomotive hearse" going up the wide staircase ahead of him as he enters his house. Following this, he sees Marley's face in all the tiles around his fireplace. It is as if Marley's is teasing Scrooge, playing games, and trying to get a rise out of him before he finally appears. To add to the drama and sense of mischief, Marley's ghost also makes all the bells in the house ring at once, and then has the cellar doors bang open.
That is quite an entrance. And then, when at last he arrives fully as a ghost, and Scrooge still refuses to believe in him, Marley is again mischievous. 

He raised a frightful cry, and shook its chain with such a dismal and appalling noise, that Scrooge held on tight to his chair, to save himself from falling in a swoon.

Marley could have appeared and spoken to Scrooge without all the drama, but that apparently is not his style.