try this. start with identifying the key of the song. If the key is A major, you would solo with the pentatonic starting on the 5th fret of the low E string. You get a bluesy feel and sound, right? but most songs dont need that feel, it just doesnt fit. Find the note of the key on the A string and move two steps up. this is your new position. If they key is A major, then use the F# pentatonic scale. Try it.