How to find out popular keywords
i have a website that provides online tutoring for a test that approx 15,000 pupils sit every year. The difficulty is that I am averaging out at 100 users signing up per year, and about 20 clicks per day. How could I find out the most popular keywords that are being used, and then it is simply a case of investing money in the campaigns?
Also how do I know that a campaign has gone live?