When DD2 was born, DD1 imploded - she used to be lovely, but she couldn't walk past baby without hitting her. She put a plastic bag over her face while I was changing her nappy, would scratch at my face and was just awful. We were also fairly isolated from family.
We tried reward charts, with prizes, also naughty step etc but what really worked for us was positive attention, so rewarding good behaviour, and ignoring bad behaviour.
Unfortunately we didn't start that until DD2 was about 8 months. I have a friend who's mother is a child psychologist, and she said you need to say 8 good things for every one bad for it to work. So you are looking at. You put your socks on really nicely. Thank you for bringing me that nappy, it's nice that you are being helpful, you concentrated really well while we were reading that story, you played with your trains really nicely, and on and on.
I also broke the day up to
after breakfast (included getting dressed)
after morning snack
after lunch
until teatime
until bedtime.
If she was good for any of those periods she got a sticker.
Three stickers in a day got a prize (usually chocolate or hairgrips)
On top of that all the stickers that she got went for a big prize - it was summer, so this was a camping trip, visit to the zoo etc.
We only use the naughty step for physical violence.
In our case the problems were all about attention, so I also gave her half an hour every night before bed when it was just me and her - I wouldtry and get the baby to bed first, but if I couldn't, she just had to go with DH.
The baby is 2.5 now, and they play together all the time, with no problems - people use them as examples of sisterly love. DD1 is still a bit of a funny kettle of fish, but that is her personality.
Good Luck