Advices to make exisitng web site i Phone compliant

Hi, the title says it all. I have an existing web site and when I look at it with an i Phone it looks ok but there are some display problems. Also, when we look at the site with different screen sizes, it is not always the same. I need someone who has already worked with web site for i Phones. I am not asking to develop a web site. The person will have access to the code and will give advices to fix the problem or even fix the existing code (available). Also I would like to have guidelines and advices for developing new web pages that are i Phone compliant and which can look the same on different screen sizes. Finally, I would like the person to answer questions around the subject. Thank you