I always used to get nervous for practicals but every time after the practical, I leave with with a brand new skill that I can go off to placement and improve on, or thinking to myself how silly I was to feel nervous about a practical. Of course at tines I had difficulty grasping some concepts but some tutors I had were very patient and went through tasks slowly as well as constantly asking students whether they had questions. Don't be shy and ask questions if you don't understand anything. It's better off leaving practicals with questions asked and answered than just having them linger in your head full of curiosity.