I really recommend the book Yes Please, Thanks! - it's fantastic about discipline. Without needing to smack for things you don't wish to smack for.

For example, you tell your child to help you tidy up. Not ask - if you ask, they can say no. "Will you do this?" is a request, "Please do this" is not. So you say "Please pick up your toy before you go out." Child makes for the door. You tell them again "You don't go out until you pick up your toy." Ignore the tantrum and go and get the child, put the toy in the hand, walk the child to the toybox and have them release the toy. Say "Thank you, now we can go out!" - but maybe not as enthusiastic a thank you as if she'd have done it on her own.

Let all hell break loose sometimes. There's nothing wrong with a cuddle and "This is the way things are, I know you want the TV but Mammy said no" every now and then. Be the boss. See your child as the adult you want her to be. Like a tree - bendable, prunable: do you want to bonsai her, stunt her emotional growth, because you let her remain a toddler because you don't say no? What would her boss do if, age 30, she chucked a tanty because she didn't want to do this job: it always worked before.