This article has been taken from: 
http://snip.ly/0m0l6#http://www.west-info.eu/a-handbook-on-how-to-avoid-awkward-social-behavior-with-blind-people/

The Italian Union of Blind People published an ad hoc handbook that gives some useful advice on this topic.

1) If you see a blind person in the street, before rushing to help him/her, ask first if he/she needs help. Being too insistent can irritate some blind people.

2) To explain to a blind person where to sit, you need to give explicit, concrete indications. In fact, let him/her actually touch the back of the chair or the arm of the chair, so he/she can be better oriented.

3) When speaking to a blind person, never use the words “here” or “there”. He/she needs exact coordinates in order to find an object or get oriented. For example, “the couch is in back of you, the glass is on the table to the left, in front of you”.

4) If you happen to be with a blind person in a restaurant, on the train, or in a meeting – let him or her arrange his/her outer clothing/accessories – because he/she knows where to leave them and get them at a later moment. Help out only in if someone asks for assistance.

5) No word is “off limits” with visually impaired people. They, themselves use terms such as: blind people, people who are blind, partially sighted, sight impaired, people with visual impairment. These words are not politically incorrect.

6) Never joke around with a blind person, asking questions like, “guess who I am?” This is in poor taste because despite blind people having a very developed auditory memory, there could be moments when the person is unable to recognize someone from his/her voice.

7) When a blind person is accompanied by a guide, do not make the mistake of asking questions to the guide (regarding the blind person), instead of addressing the blind individual directly. It is impolite.

8) When you are about to leave, be sure to advise the blind person, because, obviously – a smile or a nod of the head is useless.

9) If, while talking to a blind friend, you notice some new impediment or change in the environment, like a broken elevator or an architectonic barrier that has fallen down, mention it discreetly, so your friend can get better oriented.