ClockworkGrue's Quick 'n' Dirty, Utterly Non-Magickal Meta-Guide to Tarot Reading
With all respect to MizerieRose.
This is a meta-guide. The purpose here is to get you to understand How to Read Tarot Cards, not to actually give you a method for doing so. Methods for doing so are almost universally packaged with tarot decks, so if you have a deck, you have a method.
I've spent about five years with my deck, and most of this stuff I had to happen upon over time, by either intuiting it, or chancing upon bits and pieces scattered around in books and websites.
The Very First Thing You Should Know
Assuming you have a tarot deck, it seems more than likely that you probably have some sort of little booklet entitled "TAROT READING" or something similar. These vary in quality, but most of them aren't terribly useful, especially when you're first starting out. Now, you're not going to like this, but say it with me anyways:
"The first rule of tarot reading is that there are no rules."
Yeah. I know. You're thinking, Well, crap, man. Now what the hell am I supposed to do? At least that's what I thought when I first started out. Trust me, though, this is a Good Thing.
For starters, it means that like eating a Reeses, there's no wrong way to read the Tarot. The important thing is that you, the reader, feel like you're doing it right. This means that you can go ahead and use the method described in your dinky little mini-book thingummy. Maybe you always shuffle exactly three times, or you let the person you're reading for cut the deck. Whatever. It's all good. I still use the same Celtic Cross spread described in the Rider-Waite Tarot book.
The First Myth of Tarot Reading
Some people seem to think that if you have to look up a card in a book of readings, it makes you less of a reader. Poppycock. In the Olde Dayes, it was expected that a tarot reader would reference card meanings in a big old book of readings, much like the I Ching. As you learn more about the cards and how to tease meanings from them you'll move off-book, but that's the sign of somebody who's spent many an afternoon alone with a deck of cards. Don't be that devoted unless you really want to. Reading off-book inspires confidence in others, which is nice, but not essential.
This means that, if you look up a card, don't just look at the meanings. Find a book that talks about the symbolism that conveys those meanings. Maybe the book that came with your deck does a good job, but maybe it doesn't. If your deck uses modern imagery, you may be able to intuit meanings more easily. If it makes use of Ancient Egyptian and Medieval Christian mythology (such as the Rider-Waite Tarot), you probably aren't terribly familiar with the symbols the deck is talking to you with. Have faith. You can learn.
You Are Your Cards
We are all human. It would be nice if we could give objective readings to all people in all situations. If you don't feel comfortable with the question, be honest enough to say so. This might be because your negative energy will carry over to your reading, but it might just be that you'll use the indefinite nature of the cards to twist their meanings just enough to say what you want to say, or what the person wants to hear.
Ambiguous Questions Give Ambiguous Answers
Simple enough. If they want to know what "somebody" thinks of them, their answer will be about as murky. Remember, this is you talking here. If you don't know what they're talking about, you're not going to be a lot of help. Try to get the people you do readings for to be as open with you as they feel comfortable being. Also, during the reading, ask questions.
People will open up to you once you start describing what you see going on. Most likely, they came to you because they want to know something. Once they decide you're not a charlatan, they'll probably tell you much more than you ever wanted to know about their personal lives.
Remember that tarot cards only see the future about as well as you do. At their most mundane level, they provide a random sampling of possibilities to consider, a smattering of alternative points of view. The tarot is a tool to open your mind, and an open mind is what takes you into the best of all possible futures.