is it okay to ask for some kind of permission before making the friend add request with a girl?

something like sending a "message only" first and saying:

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Hi there,

you seems like a cool person, i'm interested to know more about you

Is it okay for me to add you as a friend?

Feel free to check my profile and let me know what you think...
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is it okay to use the above message as an opener? without actually making the friend request yet until getting her response...

and what about this opener "sending a note message with the actual friend request same time like:

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Hi there,

you seems like a cool girl, i'm interested to know more about you, i hope you don't mind me adding you as a friend...

Hit me back sometime...
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Which is better and whats about the first opener message alone, wrong or right?

and which is better from those 3:

1. sending an opener message only first and starting some kind of ongoing little conversation before making the friend request or getting messenger addy

2. send a note message with the actual friend add request same time (many social websites allow that)

3. make a friend request without writing any message along with it


What do you guys think? is it some kind of "a nice guy" approach which has low success rate?