Good question. I have spent a bit of time trying to figure out where you take your Fib levels from. To get my 38% level for the FTSE futures, I used the swing high from monday at 1pm( 5894.5) and yesterdays low at 7pm (5721.5). Normally I would have taken the nearest day's high which would have been yesterday's opening high at 8am, but for me it wasn't a swing high and was all part of the same down move from the high at 1pm on the monday.
When you have a strong move, most pullbacks tend to be to the 38% level. The price stalled just above the 5788.5 level. It faked me out slightly as I went short at 87.5 and then scratched when it looked like going higher. I should have held my nerve, but I have trouble getting the scalping mentality out of my brain, and I tend to scratch if things don't quite look right.
So in summary always take your fib levels from where the price action is. And that goes for all time frames, 5 min, 60 min or daily.