I wanted to "see things" in my twenties. Now I can see things (including one type of aura around people) without any artificial means. I see things when I focus on them more, and I see apparitions when something is being sent from my helpers. My peripheric vision improved and one time I passed through a psychic gateway at a workshop of Bert Hellinger style family constellation therapy. (the main thing is that subconsiously I was afraid of madness because I grew up with a crazy stepmother).
I guess a lot of what you see are 1. your own spirit helpers in various flashes, disguises etc. 2. other energies, spiritual presences. Some of which
are trivial, and others are safer to perceive via your own spirit helpers.
I'd say cultivate a positive relationship with your helpers (or your Higher Self, or Jesus or Buddha, whatever feels closest to you). Ask for
answers, and also practice visualisation with open eyes - simple geometrical shapes, Tibetan letters, whatever feels good. This helps observation and
changing focus if what you see is not what you want to see.
After the last time I spontaneously saw a large group of people flashing out of thin air, I got an attack of a viral flu. Since this happened a few
times over the years, I think it could also be a warning - who knows, shamans could also see viruses as some sort of group of spirits hitchhiking
You can also practice prayer or mantras to quite things down, and when it's oppressive, you can lay your own hand over your third eye, this works
especially when you lie down to take some rest.