Front end shimmy on '87 Honda Prelude?

The front end of my car shimmies mildly when driving down the highway. Mostly between 60-70mph. It is pretty bad when braking from that speed and the worst right around 40mph. I was told by a friend of mine that I should balance and rotate the tires first and maybe get an alignment because it does pull some to the right (not when braking but just driving in general). I just thought I would get some other input as well before spending an arm and a leg at some shop when it might be something simple. I know the cause of it could be alot of things, I just want some advice on where I should start this process of elimination and any advice would be greatly appreciated. Thanks for your time.....