I’m so happy that this is being discussed, we are having a bit of a crisis in our house right now. 
My girls are 8 and 10. We’ve never had discipline problems that we couldn’t handle, nothing too terrible. But lately they have developed issues with smart-mouths, bickering with each other, not responding the first time I ask them to do something, etc. It’s funny, I guess since I spend all day with them I didn’t notice it creeping on. But my husband noticed it.
We talked about it the other night and he admitted that it bothers him so much that sometimes he dreads coming home from work and listening to them. This breaks his heart, because he loves them and wants to come home to a peaceful house where he can spend time with us and rest from a tough day. So I’m trying to figure out what I can do to turn this ship around! Right now we just do time-outs in the corner, but I have to admit that they are growing out of that one. The hard part is at the beginning, I suppose. There are going to be some days where we don’t get a lot of schoolwork done because they are spending time in their rooms or doing extra chores. I’m dreading it myself, it’s going to be miserable for all of us.
My older dd is very bossy. She is a perfectionist and expects everyone to do things right (her way). Her worst offenses are bickering with her sister, and giving her orders (often repeating what I just said). I have to constantly remind her that her mother is sitting right here, she doesn’t need to tell her anything.
My younger dd responds to everything she doesn’t like with crying and wailing (like she’s 4 years old). She often waits until I have repeated myself 3 or 4 times before she’ll obey.
What kinds of consequenses should I impose? My girls are wonderful, I’m sure it’s just my lack of attention and follow through that got us into this mess.