Shred is amazing as long as it isn´t too much. To listen to a song where a guy is playn´ scales up and down as fast as he can for 5 min. is boring as hell but if you divide it and shred like 1 min. than play some cool melodies and then shred again, it can be very cool. I suggest Satriani/Petrucci/Vai formula, mixing shred with melodies and even some exotic stuff like Arabic scales. Japanese traditional music is awsome. Just listen to Cacaphony, it´s great stuff. Classic is of course nice to but it´s just so common now days.

Use you imagination while shredding but slow down somtimes. It´s good for rest and for the solo.