Hi vale! Welcome to the forum! :)
I'm glad you are interested in getting back into horses, even if it just interacting with them from the ground. Truthfully, that's often when you can learn the most about them.
In terms of approaching them in a pasture/paddock/pen, I would do the following: Relax your shoulders, release any intent from your posture. You're just there to make friends, take a leisurely stroll, yes?
Walk towards the point of their shoulder, not directly towards their head. Talk sweet, audibly announce your presence. When you reach the animal, I always tell folks to give a scratch on the neck rather than pet the face, which is what people usually want to do. You wouldn't want to be rubbed on your nose, would you?
As far as watching ears, ears pricked forward or turned towards you as you stand at their shoulder are both okay. They are alert, curious, listening to you. Ears pinned flat against the head are a no-no. Get away if that happens.
Approaching a horse in a stall is a different story. It is a confined space and therefore leaves little room for you to escape should you need to. I would not do this alone the first time, maybe with their owner present. Approach at the point of the shoulder, speak calmly, with relaxed body language, same as before. Try to keep the stall door to your back, so you may exit quickly if need be. And remember, watch those ears! Most horses loves brushing, so I'd try that first if you want to have them relax in your presence.
Good luck, enjoy your new equine friends, and I hope I helped!