I suggest joining something u r interested in on Meetup.com - will get u used to talking to (female) strangers. Find an activity class, where talking to others is natural easy part of the activity.

As u implied, don't attach importance to outcome. As beginner u should initially aim to just chat and be sociable to female strangers. Don't even think about closing. Leave closing for some future night out.

Also as beginner, don't go out cold. That is, meet up early eve with your buddies for drinks at their flat, have drinks, have a laugh. Then u hit town in high energy sociable state.

Start with this... shout HEY to get her attention, look her in the eye, epic smile, say Hi I'm so and so, you're cute....(Blah blah blah). In your head think CONFIDENCE. Hold eye contact. Good luck.