Do I use hose clamps?

[NewEnglandWinters]

Alright, so today is day three of Saab ownership, and I think this is going to be a great relationship. I picked up several crank case ventilation hoses and a PCV check valve hose, all these hoses I plan to replace today. A friend actually picked up the parts, and I forgot to have him ask whether or not I use hose clamps, or do they just slide on snug and stay put? Should I plan on going to a parts store before I start and getting hose clamps?