There are times when I've wished that I had started to learn the tarot much earlier (I got my first deck when I was 30). Then I remember myself in May, looking back at readings I'd done a couple of years ago, and wondering what I'd been thinking, to carry on in a certain situation as I did.
I've also ended up ignoring cards on few days that could have ended better, had I paid attention to them (taking my own behaviour into account).
I've gone through a couple of phases of doing readings over and over, on the same subject, hoping for a different outcome, when the reality was that that outcome was a good thing for me. With the situation I mention above, from two years ago, I wasn't completely clueless - I would back off to get my head on straight, only for one good thing to slip the rose-coloured glasses back onto my face.
Now, I do my best to only read once or twice on something, within a certain period of time, waiting until I feel that little tingle inside that alerts you to the fact that something may be changing, then I try another one. I also use them to question my own views - as to whether I'm seeing things clearly.
*edit. When I've thought to use spreads on communicating with others, they've helped me.