You'll rarely get 8:1 preflop, but I think 3:1 is enough to give some room should you actually hit your set. The money you make when you actually hit your set makes up for your bad pot odds
, especially when your opponent is holding a big hand (say a bigger pocket pair, or top pair).
Say it's a 30 chip pot, and it's 10 to call for you. You're getting 3:1 odds; maybe not good enough all by itself to make up for the poor 8:1 odds of hitting your set, but good enough to call. All you'll need to make post-flop is 50 chips to make your preflop call correct. (odds and theory wizards correct me if I'm wrong here)
I don't generally like to call raises with small pairs, but if I have some good reads on my opponent, like say he is very TAG, then his hand strength is easily identifiable, and I can maybe make a play on him if I don't hit my set. Having position on a raiser is also a must.