I was very fortunate, my mom got me my first tarot deck back in '68 when I was only 12 (still use that same deck, the only one I really like....the only one that seems to be uncannily accurate). I bought a "guide" book at the time (the little pamphlet that comes with it wasn't enough info), a little paperback that explains the meanings of the cards (upright and reversed) and some other little insightful stuff. I've seen other books, but not that interested....however, there's one that approaches it slightly differently, allows you to map out full years, etc. (that'll have to wait until I move and unpack though, lol). Also, check out some of Jung's books on symbology and the tarot - "fascinating" is an understatement.
All in all, though, once you become familiar with the meanings of the cards (it's ok to refer back to the book during a reading, I do this all the time) and the meanings of the placements, I (personally speaking) would not get bogged down in reading multiple sources of material.
For me, it seems that the tarot is a "feeling" (for lack of a better word) art, and things either feel "right" or they don't when giving a reading (i.e., the meaning of a card in a specific place...it'll feel "right" as you interpret).
What I believe about it - the person receiving a reading MUST touch the deck to infuse it with his/her subconscious. I have them shuffle a couple times while they think about their question. I never want to hear the question ahead of time, but once I lay out the cards and look them over, I will then confirm what I believe the general nature of the reading to be about. For example, pentacles are the suit of business, commerce, finances, so if there are several pentacles in the spread, I will suggest that the reading is about business/money. If they happen to say "no", I will remind them that yes it is, the cards don't lie, it's in their subconscious. By the end of the reading, they admit that yes, that actually has been on their mind, it just wasn't the primary question they were thinking about. (At which time I tell them, yes, it was the primary question, lol) Burning candles and incense enhance the process, imo.
I would start with basic Celtic layout - my favorite and preferred method - and practice on yourself, friends, family until you feel very comfortable.
Keep in mind that tarot does not predict the future, so don't let anyone tell you that. It will pick up on the person's vibes and will reveal what might happen if they remain on the course they're on. That's all it does. (Not that this isn't a great thing, lol, just...it's not going to give people winning lottery numbers or anything, lol)
Good luck and have fun!!