The Electro 2 doesn't have that much variety in terms of instruments. In terms of keyboards, the choice of sound comes down to effects, and in terms of organs, it's all about drawbar position. There are some good sites out there that list drawbar positions and other settings for all kinds of classic songs and artists. I'd figure out which artists you want to emulate first and go for that.
As for keyboards, it's fairly rare to hear clean Rhodes and Wurlitzers. Subtle delay can be really nice, chorus is often used, wah or auto-wah are good for funk songs, phaser or flanger work in some rock songs (No Quarter by Led Zeppelin comes to mind).
Play around; the Electro is an easy keyboard to work with.
