Squirrels is right on this one. There is NO NEED to be friends, in fact, it will be counter-productive. You approach them the same way you would a lady your own age or younger; what is this friends first approach; that is so lame and AFC; that approach rarely will work.
Women at that age don't want to play as many games. You have to create and raise the attraction, not the affection. Your goal is not to become her little brother type of cute little friend. Your job is to sex her up and act like a man in control. What is wrong with you guys?
Just becuase she is older than you, does not mean you can go all AFC on her. The fact that you are a lot younger does not give you a free ticket to act like a chump; specially if she's hot. Believe me, she has plenty of offers from men of all ages. She is still relatively young, and searching for a man. Believe me, the preffer a guy near her age, because she is not old.
Why would a real woman, as you seem to be convinced she is, want a little boy who doesn't spark attraction and seems to be playing it safe and try the friends first zone. Any younger guy she gives a chance to, needs to be in control of himself, and not come across as a supplicating chump. Now, if you are trying to bag some late 40's-early 50's, you will run into a lot of them that will want some young meat, no games.