Sri Sri Muralidhara Swamiji
In the name of meditation if one just stares vacantly into space, fixes the vision on a mirror or concentrates on a black dot/electric lamp the mind gets self-hypnotised. One should learn meditation directly from the Guru and adhere to His instructions strictly without any compromise. Until such time one finds a suitable Guru the safest way is to chant Hari Naama ceaselessly.
Please check these: Excerpts from a discourse by our Sri Sri Muralidhara Swamiji