No method
You just have to remember that it's all about establishing a connection. There's no point having a phone number if there's no connection. You might have as well looked it up in white pages. To establish a connection you have to have good conversation skills and a lot of confidence to appraoch in the first place. But that's pretty much it. Once you do approach, anything goes. Talk about anything that will help you establish connection and keep it. Half way through provided connection is still there tell you have to leave, but would like to continue this at a later stage (You get their contacts here, but most importantly commitment to the next encounter).
Sometimes, when connection is strong right there and then there are other options that can be explored.
Don't cry, don't regret and don't blame
Weak find the whip, willing find freedom
Towards the sun, carry your name
In warm hands you are given
Ask the wind for the way
Uncertainty's gone, your path will unravel
Accept all as it is and do not blame
God or the Devil
~Born to Live - Mavrik~