Yes it is fine to approach anybody and ask them a question, however it is extremely important that if you ask any personal information, i.e name and address, you must get specific permission from that person to publish their details, if you are using any recording equipment i.e video camera, digital dictation etc or a standard camera it is again imperative that the parties that you film/record etc are aware of what you are doing and give you full permission to use and/or distribuite any information that they give you. I would suggest that you write up a request form which you should get every individual to sign before you start any process of interviewing, this will protect you legally. Hope this helps