Girls always love being complimented, especially when it's by men that they're comfortable around. Compliment her hair, her outfit, her shoes; anything that you think she spent some time on in the morning. The smile on her face will be a sight to see right after you compliment her.
Physical contact is always a good idea to strengthen and further your relationship with a female. If you've just become friends, a fist bump is good enough. If you're close friends, you could go for a hug too. However, it is important to note that it's very easy for intentions to be misunderstood. If you're not sure what the girl thinks of you, it's best to stick to a verbal greeting.