We had a couple things for my oldest son: time out and reset time. If he totally just did something disrespectful or naughty (like spitting was a big one for me), we would get down to his eye level and say "Spitting is not allowed, it is not respectful, it is not ok. Do not do it again." If he did it again in a short period of time (we thought we needed to be reasonable for his age; if we warned him at 8am, he may not remember at 3pm, ya know?), then we would very calmly escort him to time out. We would say "Go to time out" and follow him, or sometimes have to take his hand. A couple times I had to carry him, but not usually. Time out for us: I wanted to pick a spot that I could easily see him, but where he could not be "part" of what was going on (couldn't see the TV though we could see him from the couch, couldn't see what game we were playing at the table though we could see him from our seat, just a quick peek around the corner if I was cooking, etc....but nowhere near toys or kids stuff). For us and the layout of our house, this was the corner by the front door. The dining room and entry were pretty boring to young eyes, but it was a straight shot with an easy view so I could know he was where he needed to be. I took blue painters tape and made an X on the floor, and that was the time out spot. I didn't really care if he stood or sat because he was a bundle of energy and both would be "punishment" as long as he had to stay on that one tile. For us, time out was more of a semi-stern punishment for "medium" infractions. If he hadn't really done anything wrong, but was getting wound up, I would take him to his room for "reset time". He needed to sit on his bed and calm down before he could join us, just reset (like pushing reset on the video games and it starts over) and then come back in and start over. This was also what we did if he lost his temper and I felt we were all losing control. It wasn't "the punishment" so much as a time out for everyone involved. We would say "Stop, we need to reset now". And I'd ask him to go to his room to calm down and reset. When he wasn't screaming, mouthing off (to noone because he was alone in his room) or crying, and I felt like I was calm on the inside, we'd go in and talk calmly about the situation, what was wrong with it, where we think we may have gone off, etc. We would then figure out the best discipline for us, for the situation calmly. Something that would actually be a logical result of whatever had happened before instead of everyone acting on emotions. If he chose to stay in his room a little while that was fine. But "reset" was until he was calm and ready to start over (which could be 2 seconds or 30 minutes, his choice) and "time out" was a specific, set punishment (2 minutes when he was 2, 3 when he was 3, etc....with a timer). When the timer went off, we would discuss the situation and how we needed to correct the behavior.
We love Supernanny. We also love Love & Logic (the best I've seen, and it HELPS me to keep myself under control too, since I've got a natural tendency to lose my temper or patience...this has done wonders for me, and my husband agrees). But we are big on calmly laying out choices now. Something like, I am asking you to not fight with your brother. If you choose to be nice and share with your little brother, you are choosing to have a happy afternoon and we can all go to the park to play. If you choose to fight with him and not share anything, you are choosing to stay home and miss out on your playdate at the park today. It is your choice, you tell me what you want. We do that for pretty much everything; we want him to know he is empowered to make decisions and choices, but that he has consequences (good and bad) for everything. I heard him (at 3 years old) explaining to his 2 friends one day that good things happen when you make good choices and bad things happen when you make bad choices. Had to smile....he understood enough to teach his friends, on a 3 year old level. I would try this, but you DO have to stay calm and not yell too. If you want her to not have a temper tantrum, you have to stop losing your temper too. If she needs to stop yelling, so do you....and you have to make your changes first. I'd really look into the love and logic stuff. Hope it helps. If there is a bigger emotional issue that requires therapy, do what you need to do, of course. But for normal parenting issues, this works for us.