I was browsing through this today at the bookstore. http://www.amazon.com/How-Parent-You-Always-Wanted/dp/1451663900/ref=pd_sim_b_3
It's a condensed version of some of their other books--a great set of ideas for things to say that aren't shouting or nagging.
I've been dealing with this for awhile now, and my child is 10. She's finally started to get better, but still will overreact to things. Sometimes I can talk to her and ask her why and what she is thinking.
Last year we took her to a psychiatrist, because we thought something else was going on. She had therapy once a week for a couple of months, and it really ended up being designed to give me more techniques for dealing with her behavior, I guess. He gave me a DVD called 1-2-3 Magic. I watched it and actually liked it, although I had heard of it years ago and thought AP people were against it. What I found kind of amazing about it was that I felt while watching it that he wouldn't address this completely over the top behavior, but he actually did to a degree. I didn't specifically try the techniques because I had watched the DVD with her in the room, but once I did actually reference the DVD and tell her "That's 1" "That's 2" and she got annoyed and left me alone.
She was doing OK for awhile, but then this fall she got really over the top again. I actually started giving her Vitamin D because I started to wonder if the lack of sunlight was a problem. But I really do think consistency is the key, and that is hard for me. And the not yelling is hard for me.
The other day she was throwing a fit about going to school. She had stayed up too late at night (because of anxiety and sleep disturbances, which I'm told can be diet related, but I haven't dared to go down that road yet because I know it will be a struggle), and was extremely tired. Then she was just throwing stuff around and screaming. I didn't want to send her to school like that, but she has taken too many "mental health days" as it is, and I felt like if she was really tired enough, she would go to sleep at a reasonable time that night (and she did!). On this day she said a few things that set me off, but I didn't react angrily, I just told her that what she was saying about me was a reflection of how she was feeling...she basically was telling me to stop yelling and being mad, even though I wasn't doing that. So when I hugged her and told her I was sorry she was so angry, she just cried and said she really had wanted breakfast. Since we were already late, I went back in and grabbed her something she could eat in the car. By the time she got to school she was OK, and she ended up having a good day, and then feel asleep on time that night, and stayed asleep.
When she is in the middle of a tantrum, love and hugs don't really work, although they are what I did when she was younger and I didn't want her to hurt herself or the stuff around her. Sometimes she will get angry and go outside and just take a quiet walk around the yard, and that seems to help ground her. But it is really frustrating when you ask what seems to be a reasonable question and she just explodes, especially when she blames other people for everything and how she is feeling.
There is a book called The Explosive Child which you might find useful. And maybe I would too, I haven't read it.
Gaahhh. I've been there, and still am at times! It's hard to handle because it's so aggravating, and it may take years to get better, but here are a few things that might help:
Sometimes kids really need to feel heard. I remember this being a big factor in my own frequent-meltdown phase when I was around 7--it felt like my parents Just Didn't Understand, and the more they spoke reasonably to me, the more I felt infuriated that I wasn't allowed to feel the hugely UNreasonable feelings that were overwhelming me. With my son, sometimes just a few sentences reflecting the ideas he is expressing ("You get tired of picking up so often. It feels like a lot of work.") with pauses to let him fill in some more details, will get him more receptive to the inevitable ("The Legos need to be put away now."). I try to say it the way Mister Rogers would; that's my best strategy for keeping my tone calm. Sometimes it helps to empathize with his feelings ("I get tired of picking up, too. I wish we had that machine the Cat in the Hat has.") but it's crucial to avoid letting that turn into criticism ("That's why I hate picking up YOUR junk! I have enough to do already!").
Resist the urge to argue about how you did not either yell at her. This never helps. If she feels like you yelled, then in her reality you yelled, and you're not going to be able to argue her into your reality, but the argument will be unpleasant for both of you. (I keep learning this again and again. ) Also, it's a diversion from the real issue at hand. Just watch your tone going forward, and continue to speak firmly about what needs to happen: "When you have brushed your teeth, then we can read a story." (The "when...then..." phrasing can help remind the kid that the task she's resisting is a necessary step toward something more pleasant.)
Full-day kindergarten can be a big adjustment--it was for my son, even after 3+ years of full-day preschool, because although his kindergarten day was actually shorter it was much more structured and had less downtime. Try to find a way for your daughter to feel really comforted by coming home, have a calm and loving way to settle in and relax a bit before she has to do anything like unpack her stuff. If she is energetic then and wanting to play play play, that's fine, but be prepared for a sudden loss of energy and drop in mood. A high-protein snack may help her stay level. If at all possible, avoid running errands on the way home from school or any other tiring distraction.