If i want to tone up (build muscle) and be lean, what would be an ideal lifestyle diet? i am 5'6 122 lbs with 19-20% body fat (goal 17-18 % body fat)

Many ways: There are many differing opinions in this topic. Importantly you must adopt a lifestyle of fitness ; nutrition that works for you. In this regard you're more likely to enjoy your program and will likely adhere to it. I personally like the cross training discipline, which involves a variety of sports including strength training and good nutrition. I recommend assistance from a sports trainer.