I cant believe that people make this mistake.
Hard to find or missing contact details. Nothing gets me more angry that finding a product or service that I am wanting to learn more about or purchase and not being able to easily find the contact details. It is such a simple thing to have your contact details upfront and easy to find.
Today it is so simple to integrate with Social Media, so why not add a Facebook page that will allow visitors to contact you fast and easily.
Also, if you have a shop or specific operating hours…list your opening hours, its not that hard.