Unsure on what spec to use when levelling

When I hit 60 I intend to go Holy to heal.
What I am unsure about is what spec to use when I am levelling. I would like to be able to both tank and heal dungeons. I would also like to be able to quest easily. Once I hit 55+ I'll probably drop tanking instances to focus solely on healing.
Could anyone suggest a good spec (and in what order to spend the points)?
Thanks.
What I am unsure about is what spec to use when I am levelling. I would like to be able to both tank and heal dungeons. I would also like to be able to quest easily. Once I hit 55+ I'll probably drop tanking instances to focus solely on healing.
Could anyone suggest a good spec (and in what order to spend the points)?
Thanks.