yup...record yourself doing backup chords then play leads over top of em. Better yet, if you have midi, download songs off the web and just make up stuff to em. Something like Band-in-a-Box is good for improvising too cause you just input the style and chords you wanna use & you have a backup band ready to go.
As you progress and learn more scales etc... you'll find yourself using bits & pieces of everything you've learned, like little bits of leads, hooks and tricks etc.. and incorporating them into your own leads.
The height of improvising is when you can play what you hear in your head without struggling to find the notes...so the more you learn how to navigate the fretboard the easier it'll be.