This is how your website interacts with your potential customers and there are many ways of doing this. Information is key here and you must provide as much as possible so that visitors feel confident in doing business with you.
At the very least you should provide an email address, but beware of a simple hyperlink on your webpage as this will quickly get harvested by the spammers and your inbox will be clogged in no time. The email address can be disguised by just stating it in text without the @ symbol, or you can use a simple script that does not reveal your actual email address to a browser. If you get an enquiry, be sure to always respond as soon as possible. Quite often big businesses are not able to do this and you will boost customer confidence no end if you can achieve this.
I prefer to use a contact form which the visitor fills in. This way you can find out more about your visitor and where they come from. Form scripts are readily available on the net, but be sure to use a secure one.
A telephone number is an obvious contact detail to include, but it is surprising how many sites do not give this information. It is possible to get a national rate number which provides you with a small payment each time someone calls, but this temptation has to be weighed up against the possibility of consumer resistance! You may not wish to put your address on the web site if you work from home, but it is easy to set up a post office box number address if you prefer.
You might like to include a newsletter sign up facility to harvest the email addresses of potential customers, but not everyone wants to reveal this information. If you are normally on line during your business hours you could set up an on line help system so that a customer could ask a question and get an immediate response. This is a big commitment but can work very well.