if you seek to enter samadhis, then eyes closed and darkness are fine, but from a zen perspective to meditate with eyes closed is entering the dark demon cave and is fruitless. zazen and shikantaza are what you see right in front of you right now. within and without. that is enlightenment.
do you see this post?
do you know that you are reading this post?
do you understand these words?
am i enlightened?
i am Tom.
the best piece of advice i can give for meditation is just to see what you see. and thats it. no need to focus on the breath. this is meditation all the time, whether mindful or not. formless meditation.
entering samadhi by focusing on the hara is all well and good, but direct ordinary seeing is better. all becomes zazen, no need to sit on a cushion. eating is zazen, talking is zazen, seeing is zazen, seeping the leaves is zazen. just ordinary awareness is zazen. when you see this you just see it. its ordinary seeing and ordinary mind seeing it. this is like learning to appreciate water, without flavour you just see.
some people are too bussy to formally sit during the day then all becomes ones zazen. to meditate at night can be fine, but owing to tiredness its best to set aside a slot in the early evening. i would advise that you meditate without meditating, ... sit zazen whether reclining or lying down with eyes open. you are already a master of zazen. everyone is. just see, smell, hear, feel. ordinary mind is zazen. ordinary mind sees in an ordinary way ordinary things.
zazen is enlightenment. ordinary mind. just like that!
what are we looking for? its right infront of us. thats zazen, thats shikantaza.
best wishes, Tom.
in any matters of importance. dont rely on me. i may not know what i am talking about. take what i say as mere speculation. i am not ordained. nor do i have a formal training. i do believe though that if i am wrong on any point. there are those on this site who i hope will quickly point out my mistakes.