This is an old chestnut on Mnsnet so apologies if you already know about this book, but can recommend having a read of:
"Unconditional Parenting" by Alfie Kohn
Personally, I think it goes too far but there is a great deal of sense in what it says.
Basically, before I knew beter, I tried the very strict approach with dd without success. It put us in to daily conflict over a myriad of ridiculously small issues. And it didn't work. She simply didn't listen because I was always saying 'no' or criticising.
The following paragraphs sum up the main premis of the book:
" Let's put aside for the moment the ambitious goals we have four our dc and just focus on what leads them to comply with our requests. If all we cared about was getting them to do something, or to stop doing something, right now, while we're standing there, then we'd have to admit that it sometimes work to use our 'power' to coerce that behaviour - for example by threatening, punishing or loudly demanding. But only sometimes.
On balance, the kids who DO what they're told are likely to be those whose parents DON'T rely on power and instead have developed a warm and secure relationship with them. They have parents who treat them with respect, minimize the use of control, and make a point of offering reasons and explanations for what they ask.
The researchers in one classic stuy began by distinguishing between the sort of parent who is sensitive, accepting and cooperative, and the sort who assumes "she has a perfect right to do (with her child) what she wishes, imposing her will on his, shaping him to her standards, and interrupting him arbitrarily without regard for his needs, wishes or activity-in-progress"
Lo and behold, it was the mothers in the first category - those who were less controlling - whose very young children were likely to do what they were told.
In a second study, the two-year-olds who were most likely to comply with a specific request turned out to be those whose parents "were very clear about what they wanted, but in addition to listening to their dcs' objections, they also accommodated them in ways that conveyed respect for the dcs' autonomy and individuality"
Not for a moment suggesting that you are too strict Jennymac but I HAD gone to far in that direction before I read this book and - although it is of course much easier 'read' than done - it has really improved my relationship with dd.
It was when I realised that one can't - or shouldn't try (within reason of course!!) to control a child that - ironically - dd became more easier to control.
Sorry for the essay but it's a bit of a hot topic for me at the moment.