>>Meditation on oneself, looking deep within and nidhidhyAsana (contemplation on what is observed), the silent One within and without - does make you eventually realize the mahAvAkya aham BrahmAsmi -- as told by the shAstra and AchAryas, but before that, the deep presence of Brahman pervading space.
Once convinced of the formless - nirAkAr Brahman in the golden silence outside, it is then easy to go inside IMHO.
>>Go to a height, like a hill, or an open space, maybe lake shore or ocean shore. Look as far as you can -- gives a feel for the vastness and still silence of Brahman's presence outside. => this does not immediately jump to "sarvaM khalvidam Brahman" because at least for me -- this makes evident the presence of the nirAkAr interwined in the physical world. but not yet the physical world. For that, more observation outside , nidhidhyAsan and the tat-tvam-asi realization goes hand-in-hand.
tat-padArtha is not yet extended to the physical universe. For me, the nirAkAr and sAkAr is a Person, the same Person , Highest AtmA ('Self') of all -- and that is real me. This may be different/a deviation from the common understanding. Communication with the nirAkar ends up with the same sAkAr bhagvAn.
>>OR look at the vast open sky a few hrs before sunset - the sun has to be in the sky, and make sure the panorama does not have manmade constructions like tall buildings in the sillohoutte.