I noticed in both your scenarios you were trying to draw back on the deer when they noticed you. I know its not always a perfect scenario when a deer comes in but I also know from my own experiences and helping others get started in bowhunting that your first reaction when a deers coming is to get the bow up and get it drawn back.

When Im hunting with someone new to the sport and they get busted trying to draw back often I tell em to just watch a deer they dont plan to shoot as it comes past thier stand and count how many times the deers actually looking completely away from them as opposed to having its head up and being alert.Because if you really watch a relaxed deer they will generally give you several oppurtunities to draw undetected, they put thier head down and nibble on stuff, stop and turn to check thier backtrail, stop with thier head behind a tree or brush, etc... and they do it often.These are much better times to draw then when they are walking straight towards you down a trail.Again, I know its not always possible but 9 out of 10times the deer will give you at least one good chance to get drawn.They will often ignor you if your not moving, if they see movement theyre gonna be on high alert and be gone.