Do some ski-abs excersicing and you should also try squats. I recommend to start off the first day with 5 to 10 and increase as the weeks go by.
Try Pilates...I've done it for years and find its fab for those areas as well as abs. I follow blogilates with cassy ho. She has a YouTube channel and websites with loads of beginners videos for you to follow. She also gives you a monthly workout calander to complete using her YouTube vids :)
Squats and lunges and step--up exercises. It is very important to do these exercises correctly to get the effect and protect your back, so working with a personal trainer will help you the most. But the trouble is they always suggest squats and lunges and people don't want to do them. There is no avoiding them.
Do you go to a gym or is this going to be at home? If it's at home do you have any equipment?