What other places do you recommend for beginners besides the park?
The best places for me are wherever the flow of traffic is slowed or stopped.
Architecture has a very powerful effect on the way people behave socially, and their mood in public. Especially in older cities, you have plenty of large communal spaces of different kinds where people congregate to relax and mingle - places you might say that have an ambience that they enjoy lounging around in. In these places, people are much more open, much more outward focused, their restless energy turns into a more reflective, relaxed one, their fast march turns into a wandering stroll. In short, they are much more open to meeting you.
On the other hand, when you have narrow footpaths of officeblocks with cars hurtling alongside you, and every few hundred metres you have to walk right past a dank alleyway, naturally people are going to be on high alert, walking fast, and with defenses up. Not to mention that you could only approach really from directly ahead or directly behind. Almost everything is going to be startling.
In the mall, I find the sheer mass of people, noise and activity makes women simply tune out of their surroundings, put their defenses up, and march around focused on what they want to buy or whatever.
So I've found the best places to be parks, courtyards, plazas and public squares, riversides etc. They tend to be where someone goes for a breather to get out of the matrix for a while. Beside the river is where I've had most success. But the river is just a symbol - other places have other symbols.
The most difficult places are narrow funnels of traffic, places that make you feel like you have to be moving fast or you're an anomaly in the matrix, any place along her route to and from home (people are protective of their 'territory'), any dark or too far out of the way place, or places that feel boxed in and have few or one exit point.
Pay attention to your impression of an area - is the ambience blaring and annoying, does it make you feel like you need to be alert, etc. Whatever your impression is, she probably feels 100x stronger. Also, pay attention to the way women behave, her body language, in different areas. They love being approached, and meeting men, but do not like being startled or feeling pressure by having it happen in a way that is so out of place with their expectations that they are virtually forced to reject on the spot.
Now I am NOT saying it's impossible to pick up girls in these areas, or that you might not be able to get some very positive reactions, but generally speaking it's where I find women least open to meeting strangers. Calibration is key. I've picked up girls in shops and along random streets. But I'm also good at picking up IOIs, reading her mood and demeanor, and above all, at re-calibrating very quickly to new information. It takes a while to develop that.