One of the things that people find most confusing when playing the violin, is how much tension to use in your muscles. And the answer is... not much! Obviously we need *enough* muscle tension that the body doesn't collapse or drop the violin, but we don't really need much more than that.
Now, this can be a difficult concept, especially for adult learners, because in our day to day lives we use a lot of physical tension to pick up objects. We do this naturally, to be sure that we're holding onto objects properly - otherwise we might accidentally drop them! It's the same if we're using a button or a switch, or maybe typing something... I don't want my finger to collapse. So instinctively, we tighten the muscles in each finger before carrying out the action.
Now with the violin and the bow it's a very different story. If we 'grip' them hard, as we do with other objects, we won't be able to move them in the way we need to. So you have to handle them with very very 'soft hands'. Imagine you're holding a small kitten or a delicate piece of pastry and you don't want to use any more 'grip' than is necessary, because otherwise you might hurt or damage whatever it is you're holding!
As you pick up the violin and bow, make sure that you're only using as much tension in your hands and arms as you need to, and nothing more. This is important because, if we grip the bow with unnecessary tension, it's going to affect the sound. We need the muscles of our hands and arms to be extremely free and relaxed, in order to get the most beautiful sounds when we play.