Uh.!?

Me and my SO have messed around a bit. We've had sexual relations, I've given him hand jobs. But I've never given him a blow-job. I'm scared I'm 
Not gunna do it right. I don't know what his penis is going to taste like. Or how his sperm is going to taste. Or how's it gunna feel in my mouth.Any ideas? Any tips? I need help I know TMI but please be descriptive.