An acquaintance of mine is building a website for his (non-profit) organization. Since I'm currently an automated tester on a desktop-based application, I thought I could help him do some web testing. I don't have much experience in web testing but I'm aware of a few different areas of web testing like user experience, security, and performance. The site will be built from basically scratch, and I won't be writing any of the code on the front- or back-end (at this point anyway). I'm definitely interested in creating some automated test scripts using Selenium but how should I approach testing a web site that's brand new? Are there any generally good approaches for preparing to test in such a situation?
EDIT: Although I'd like to create some automated tests using Selenium, I'm not definitely not going down a "automation-only" or "Selenium-only" route. Any testing directions or ideas would be appreciated.