Aliens can visit race to race by using technologies that effect it, including dimensional technologies.
They also most naturally use spiritual abilities, as in visiting out of body and speaking by telepathy.
They also use both technologies and natural abilities together.
One way as that they can be inside of their space crafts with their normal atmosphere, make their space crafts be invisible.
Land right where we are but in the next dimension, and then allow us to see themselves.
So in effect, we may assume that we are having a face to face meeting.
We would be somewhat aware of the effects of the technologies, and there would be limitations, such as not being able to touch them.
And these things could "blow our minds" to witness if we have no tolerance or understanding.
Our Personal Meetings
They can meet with us at any time, anywhere, no matter what we are doing.
They try to plan meetings at night whenever possible because it is easier and less disruptive to our lives.
There are many ways they can get in without opening or moving anything.
It is very easy for them by technologies and natural abilities.
They can project themselves naturally to be right where you are, out of body.
They can also move through solid objects by rearranging the molecular structure of them and can also pull you through them with no harm to your body.