yeah ask them to give you there analytic software user and pass Do one thing..check there title tags, meta tags, content, backlink ancohred text. this will give you a good number of keywords. go to wordtracker and check there daily counts and you get a good idea what to do with them
as seoz87 says, have a look at the title tag on their index page, there should only really be 70 characters so it cant be hard to figure out which 5/6 phrases there targetting for on the home page, it will be one of these phrases that are bringing in the most traffic. look for the phrase they are highest up in google for, that SHOULD(but not always) be the biggest traffic bringer
Before you can see keywords of your competitor on seodigger.com but it's close now but they have new product now on SEMRush.com same as seodigger but it's paid.
Thank you so much for the replies. Of course I know to look at things like title tags but this particular competitor comes up in many different searches as our business requires multiple keywords and has about double the traffic that I do. It's not like we are promoting only one thing so we have many keywords to target. keywordspy was very helpful but I'm not so sure that it listed the top referring keywords in order. I will try out the others listed here next. Thank you!