yellowed

My Phal orchid doesn't seem to be doing well. The lower leaves are yellowing and all over its color looks rather dull. I thought it was doing fine until I saw some for sale in the nursery with beautiful dark-green glossy leaves and gorgeous flowers. I asked the nursery man if they required special care and how you get them to bloom again and he just shrugged: "if you give them the proper care, they just do their thing" and rebloom again and again. So I'm not giving it the right care? I think it needs more sun. I've moved it into the windowsill and hoping for the best.