Simply meditating on your third eye works, and it works for me if I say some mantra while in meditation. I also believe a tea of mullein, coltsfoot and mugwort help.
It can take a while to see orbs/spirits, but it isn't impossible, you simply have to put your mind on the fact that there are spirits among us, and that you want to see them. Once you have this mind set, this belief, then you'll start to see spirits. Meditation does help.
Generally, in my experience it helps if the room has a lot of energy built up already. You can do this by playing music that you enjoy, either it be dark or just full of some sort of energy. Chances are that there'll be more spirits present. To get dark orbs to come, and you may feel drained and depressed if you bring black orbs into your presence, just play dark music and sing along with it.
Or you can get into a heated discussion with an enemy and notice to watch for at least one black orb to buzz around.
Kind of fun playing with different energies, but the black ones can make others depressed and drained. The white orbs I don't know what to make of, but I've seen them circle me one time while going for a run. I'll call them nature spirits, because they seem to be the only thing natural.