What Tom and Rondo said..........
You only want enough light around the rear sight to let you know it is indeed dead centered.
As far as how far forward that rear sight goes is totally dependent on your personal eye sight. You do want it to be clear as a bell.
Glare is certainly a problem for many.
"Smoking" the sight with real smoke, or actually real soot, is the only answer that has proven totally reliable over many years.
Magic Markers are a great quick fix, but if your front sight is smooth, and not steeped, you can still get a little bit of glare even from that.
Old Zippo lighters works better than modern day matches, a "Beeswax" candle, held away from the sight so the soot from the wick will form, works even better than a Zippo.
I once had a "sight-black" can I used to use, and it held 1/3 cup of kerosene with 1/2 tsp motor oil added.
It was ugly, dirty, messy, and totally reliable.
Of course "sight-black" is extremely fragile, touch it with a cloth, a patch, your sleeve, whatever, and it's gone.....however, it's still rated as the best.
Uncle Russ...