You should be able to ask for direction, so long as it's phrased in a way that is pleasing to your Master.
For example, if you want some more guidance about your wardrobe, some doms would be pleased if you asked "Does what I'm wearing today please you, Sir?", where as others might prefer if you just flat out said "I would like to wear things that please you, what might such things be?"
I am of the variety where I prefer direct questions, so for me, even if you said "It would make this one very happy, Ma'am, if you would please tell me what to wear." But I'm not easily offended.
It all depends on how long you've been together with your dom. If you've just met, then I think such questions are perfectly valid and necessary. If you've known each other for a longer amount of time, then you would be more equipped to be able to simply know what makes your dom happy, and just do it, like denu said.
Sometimes you can just pay attention to his reaction to things. Obviously, if something you said or did made him happy, do more of it. There is a lot to be said for paying attention. To me one of the sweetest and biggest turn-ons a sub can do is by surprising me with something that pleases me when I didn't ask for it. For example when my little one somehow figured out what my favorite album was when I was a teenager and he bought me the CD, can I tell you how much I adored him when I had something I loved like that and thought was lost forever in my hands? *sigh*