Living in a crowded city, I got pretty good at it. To me there's three parts to the initial move
You end up making a S curve. The key is the middle part. That's what gets you close to the curb, if you move to the reverse turn too quickly, you end up too far out. You don't want a wide S, you want a long skinny S. As you come out of your first turn keep the wheel straight for about a 2-3 count and just go back as far as you need before beginning your reverse turn.
I use to think of as one S curve move, but it didn't work well, thinking of it as three separate parts helping me visualize what the car was doing.
Another tip is if the spot is really tight, don't try to get closer in each direction. One direction is for getting close to the curb while the other direction is for going straight forward and getting as much room as possible to back in again. Make your intial S curve and get in as far as you can. Then straighten the car and pull as close to other car as you can and do another mini S curve backwards. Otherwise, you end up with front or the rear sticking out to far and you can't get the car straight.