The problem I have with Fibs is that there are many different swing points to use. Sometimes you can use the overnight low to start draw from, or sometimes the low after the open. So now you have two ways to draw a low. Then you maybe see some obvious high 30 mins or 1 hour after open, so you start drawing. You might consider the 38%, or 50% or 68% fibs. So you have 3 combinations, but with 2 starting points, its now 6 different possible turning points.
I like what Ram said about the "go" signal, but it then sounds like this go signal is most critical, and maybe you can even do this without the fibs. Simply seeing price dropping with volume might be enough to enter a short, even if it didn't hit some fib level. I do believe in overnight levels, previous day highs and lows, previous day close, that sort of thing, so that already provides plenty of levels.