There are no real rules for lucid dreaming--if something works for you, then go for it! If music relaxes you but still keeps you awake for the WBTB, then listen to it.

Personally, I wouldn't recommend stuff like TV or the computer, but like I said everyone is different. For me that kind of stuff makes me zone out too much and I'll just dream about watching a screen (which, BTW, is the hardest type of dream to get lucid in IMO).