My 2 cents, as im getting into cold approaches now after a long time and even then just a handful (10) cold approaches in my life. But I think I am going to be going in hard now as I am a different person with new perspectives.
So this is what I am doing atm. I got 1 number from 3 approaches and I think shes into me. The other two went okish but made some mistakes mostly around not having a plan for after the open and basic convo.
Open: Hit the open assertively and then keep fun convo flowing. Be nice and validate assertively after the open. Your masculinity and confidence is basically there to make her feel good about herself. Be nice and hit her with some good compliments/validation after you open and then go into a convo just bantering, keep it simple and fun and ask questions to show interest in her and for you you are keeping it light and fun. Dont try to be clever or any lines or anything. Do not over validate or compliment, this is just for the open but can be added to depending on the convo.
The open I do: Always approach from the back when shes walking, come side by side, smile, be confident and say hi. Your first hi is softer because you are showing that you respect her personal space. They will not respond the first time but will react subtly. Smile again and again say and then just go into "hey hows its going" or something similar. Now she might respond a bit more with a headturn. Then be nice and say some nice things about her. Keep is simple compliment what you can see about her, dont say anything about looks talk about style, clothing etc Show that you are happy to be saying these things to her she will love it.
I approach from the back and go side by side because normally they are walking and thats the only way I can approach. I find the one I want and follow until an opportunity comes up. I do not approach her from the front because that would need her to stop which is an inconvenience for her and also a notice of interest which women usually dont want to give. Show with your body language that you respect her personal space and are willing to walk away to not cause her distress, cos you are not one of those touchy feely guys.
Keep the convo light and fun. Your initially positivity will carry through into the convo and she will be happy that a confident guy (I dont know how you look or act) approached her and made her feel good.
At this point I need to figure what is the best way to progress but I do have some ideas I wanna try out.
Its important not to come on too strong and always say thanks and let it go if too much negativity or indifference is shown. You do not wanna get a number of a girl who doesnt really like you. Focus on positivity but that initial positivity has to ride out till the end. You cannot turn any resistance into a positive so no forcing the convo or asking her to stop, or being needy. Maintain your dignity and be able to walk away with a smile and a nice to meet you at the slightest disinterest.