It depends on what you are using under the float.
The very first thing to get right when float fishing for salmon in the Vedder, is to balance the float correctly. This means, adding enough weight to sink the float so only a coloured top of the float sits above the water surface.
Once you cast your float you, try keeping as much line between your rod tip and the float away from the water as possible. This means lifting your rod up so line does not fall down onto the water surface, but don't lift enough to pull the float back and away from where you want to drift. It's a balance between avoiding a belly of your main line on the surface and maintaining a natural drift of whatever you are fishing with to entice fish.
If I am fishing with roe or something that imitate eggs, I like to keep the drift as natural as possible. This means, I try to avoid creating any resistance on the line. I want that egg in the water seem like it is drifting down freely in the current. If I am fishing with a spinner under the float, then I usually create a slight resistance to the line so the spinner would spin. If there isn't that resistance, then the spoon/blade would simply flutter in the water, which isn't necessarily a bad thing as it also catches fish.