A bit from +Chris Perkins that works well with DW games, I would think.
“I exhibit a low tolerance for player indecision in combat. Combat is supposed to be fluid and fast, and nothing causes the game to grind to a halt faster than an indecisive player who can’t decide what actions his character should take on his turn. I will press the player with questions such as, “What does your character do?” If this doesn’t push the player to swift action, I ask, “Would you like to delay?” (which, if answered in the affirmative, lets me skip forward until the player decides he’s ready to jump back in). Other favorite sayings of mine include, “You can always use an at-will power” or “Do whatever feels right for your character.” Another thing I do is have a monster or NPC verbally taunt or insult the character, which often incites the player to take immediate action against the offending enemy (and also breaks the lull with a touch of roleplaying).”
–Chris Perkins, quoted from the midst of lots of good advice at http://www.wizards.com/DnD/Article.aspx?x=dnd/4dmxp/20110901