The safest technique is the practise of Transcendental Meditation which is effortless and the student of meditation remains in a state of restful alertness and does not have any attachment to the thought process relinquishing all desire just being rather than doing and allowing the mind to transcend the relative level of the mind.
Please, do *not* try to clear your mind or close off all thoughts. After all, who is doing the clearing? It is simply another part of the mind!
Meditation is all about simply being present to what is, without judgment or expectation. If you notice thoughts, good! You are noticing thoughts, and it is the *noticing* that is the awareness, the meditation.
If you notice feelings or physical sensations, good! Simply watch, without analyzing.
Again, if "you" are pushing thoughts away, who is doing it? It is just another part of the mind, and awareness is beyond the mind. Awareness is like a mirror -- it simply reflects what is in front of it, not trying to change or fix it. If a handsome man walks in front of a mirror, the mirror shows him. If a man with a scar on his face is there, the mirror reflects the scar.
This is how your meditation should be -- simply accept what is.
Different people experience different things when they meditate. It sounds like you have been meditating, and you have seen "visions and light fields."
After fifteen years of meditating, I can tell you the mind will create all kinds of thoughts, images, and dreams to distract you from simply being present to what is. I have seen all kinds of stuff, and thought all kinds of thoughts while meditating.
What I have learned is all of it is not significant. It is all the same: it is all mind stuff. And meditation is about coming into contact with that which is *beyond the mind.*
So when you see visions, simply watch the visions, just like you would watch a thought or a feeling. This too shall pass.
Over time, little gaps will arise between thoughts. In these silent moments, blissfulness will arise.