Chairman, are you me?! Mine are also 7 and 4 and I love How to Talk, although am generally crap at making it work when they are kicking off. The 7 year old is being a nightmare at the moment, making an absolutely massive fuss about loads of things. Eg school want her to read five times (!) a week at home with an adult and she had just flatly been refusing, despite being a good reader, and this being a relatively easy thing for her to comply with. Cue cajoling, then shouting, then general despair from me.
However....two things I do do which work are not disagreeing with them when they are expressing a thought or feeling, however ridiculous / unrealistic I think that might be. You don't have to actually agree that their feeling is a sensible reaction, you just have to acknowledge that that's what they are saying they feel right now.
So DC says in the morning "I'm tooooo tired to put my shoes on". Instead of "You can't be tired, you slept 12 hours last night, and anyway we are late for school, PUT YOUR SHOES ON, I ask you every single day! JUST DO IT!", you say "Hm, ah ha, it's tiring going into Y3 isn't it, time to put your shoes on".
Takes the heat out of the situation sometimes. I read on here "you don't have to enter into every argument you are invited to" and that's so true.
Also doing the "being silly" thing. So DC said "I'm thirsty" in the car when we didn't have any water. Instead of saying "We don't have any water", cue DC kicking off, I said "Afraid we've run out of water. I wish I could give you some water. I wish I could SQUIRT you some water! [pretend squirting with sound effects]. I wish I could fill the WHOLE CAR up with water!" etc. Doesn't particularly come naturally to me, but it can work.
Off to read Brenda's thread - I am very much in need of a lot more help with my parenting....