I'm a new fan of the Park der hanger alignment tool. It's simple and effective.
It's not necessarily the best $$ investment for an average, single road bike DIY'er, but ... if you don't want to buy one, find an LBS that has one, and knows how to use it, and have them check your aligment, and use it to straighten it, if necessary.
My $0.02. YMMV