Yes I'll do yes/no with one card in TdM but negative and positive tend to be numerically based. Some numbers are far more harmonious than others for me. Some are cards of balance and harmony, others are cards that talk about a lack of balance. Then I add in what suit the card is (if it's not a major) and the idea of disharmony in the suit of cups brings its own conclusions; and so it goes for each suit. If the card is a major, then I would be thinking about the meanings I associate with it; asking whether I should go to a party and pulling L'Eremite is pretty conclusive, no?
More frequently I work with sets of three cards just put out in a row and see how they talk to each other. I tend to ask "what if" and look at the three together more than straight yes/no. Or "how would this affect the situation?". Mainly I suppose because I find yes/no very limiting; I always want to know how and why and what.
Also I look at what the vines and flowers are doing. Flourishing? Withering, or being chopped off. Or is there something blocking the upward progression? And see which way curves flow - away from each other, or towards? Are the flowers open and inviting, or closed off and isolated? Stuff like that
Incidentally, the TdM section here is a fantastic resource
http://www.tarotforum.net/forumdisplay.php?f=38 and the index thread
http://www.tarotforum.net/showthread.php?t=158719 is very useful indeed. Personally I dive into the old threads and just lose hours! Great fun and so very informative