Mancfly's advice on floats is spot on,a shouldered stick type float will allow you to hold back which basically means trapping the line against the reel spool and stopping the passage of the float downstream for a second or two.
This will cause your hookbait to rise up in the water and then fall again(when you release the reel line)and can induce a take.It s not possible to hold back in this manner with the waggler as trapping the line will cause it to sink.
Steve