How do you make sure people don't walk into glass doors?

You could hang some sun catchers on them. You can apply some vinyl type appliqués in a whimsical style. You can buy both at the dollar store especially in early spring. Or if you're talented in painting you can paint flowers or vines on the glass. Or you can find vinyl window coverings in various patterns. Sort of like a contact paper.

I paint on them with acrylic paint, and often just change it 'cuz I like painting!

You could tape off a pattern and use etching cream between the taped sections.

Home Depot and maybe Lowe's has something called "Light Effects" that comes in a roll. It gives a frosted effect. You can place this in a long strip or put in a pattern and put on the glass. They also come in a stained glass pattern. Beautiful.

Here's a solution I love!

http://www.hometalk.com/diy/windows-doors/windows/privacy-glass-using-contact-paper-27032870

You can hang strings of little clear beads that will dazzle in the sunlight and can easily be made from fishing lines and beads from wal-mart. you can add different colors too if you wanted, to change for holidays. Just hang them with those little suction cups. Hang them high enough though so pets and kids won't get them. The decals work best though I would think. My niece went racing through and tore down a screen door I had, it was funny, she was terrifed I was going to be mad, but she was little enough, it did not damage. lol so think about something for the screen door too. maybe some kind of flat magnets on each side. Not sure how strong they would have to be to work. hmmm! If it is your home, you could paint on the screen.

I buy those little flower shaped stickers that double as insect repellants. I put one low down so that the dg doesn't run into the glass sliding door and it works.

Stikeez window clings. Google it. My son learned his numbers and letters from the stikeez my mother put on her patio doors. He's 20 now and there are still some stars on the doors.

Don't wash off the blood. Nothing like a hint to get the attention.