You can see the hole under the arm/bracket if it is not plugged up with dirt. Try shining a light up from the bottom to make the hole easier to see from the top. It is still hard to see.

I really cant say the best way, just the way i did it. if i was to do it again, I would stick a nail thru the hole, and spin the spring until it stops on the nail. The last few times I did it, I did have the spring out, and I lined it up by looking up from the bottom and feeling the spring into the pocket. I was doing it without a compressor and with the lower arm loose from the bushing side.

I needed help with the 6312 springs, but I did the 6308s and chopped springs by myself.
The taller 6312 springs needed 2 people on the front of the car to make it heavy enough to compress the spring, and then the car sat with the shocks almost topped out.