Using Tarot Deck As Medium Options

So I've been experimenting with this theory that popped up in my head. I know this might sounds very silly, especially coming from a newbie like me, but please bear with me a bit (IMG:style_emoticons/default/wink.gif).

We all know that Tarot is full of symbolism and interpreting it to some situation and position took a lot of creativity, right? So I've been wondering if I could use it in a ritual as a medium to deliver my will. For example, I used my interpretation of The Strength to help fixing my friend's relationship problem (giving him more patience, that is). I did charge my card through meditations and some sort of offer-to-deity kind of way.

So far, my friend's relationship haven't improved that good, but that might because I lost my deck. My now-ex-girlfriend took the card away from me for she said that it "consumes me slowly".

So what you guys think about my experiment? Should I continue doing this? If so, should I try to re-possess my card or should I make another one? Any advice or maybe a reference reading? Old Theory I might miss?

Any help is greatly welcomed (IMG:style_emoticons/default/smile.gif).

Acid, I am interested in the point you made about not believing in something negates harmful effects. I have come across many people who strongly believe that but I am not sure. I defiantly would agree that a mentality of that sort is generally positive, but I am not sure it is generally correct. It isn't easy to argue really but I would have to say I think the best, most powerful counter magic would be some form of banishment or counter magic, not harmful but a defensive counter. I'm not taking about fictitious wizard battles either. Also making the best within the context of possibilities of the moment might be the good too, if that makes any sense. I guess I'm more thinking out loud than anything here.