More importantly, make sure youre float is dotted down to the merest dimple.
This way you weil see the slightest movement, and wait until it goes under.
A trick of the match lads it to shot the float so that it "just" sinks.
What you do then is to smear the top of the float with vaseline, so that only the tension of the water is holding it up.
Use this method for fishing just off the bottom.
If you are fishing on the bottom, say by 6"-8"
Try either deepening or shallowing up in order to give the fish more time to take the bait properly. This last part is trial and error.