I also like GBPUSD. It is my favorite pair because it has nice big moves and relatively small spread.
Any pair you choose, you should establish the most corelated pairs for it and watch for the same signals (or the oposite signal - if the corelation is negative). I always check EURUSD and USDCHF before trading GBPUSD.
EURUSD tends to give the same signal and the USDCHF tends to give the oposite signal.
Due to the nature of this pair, I set my SL to 35-50pips. So, the risk/revard rule is making me to set the TP to 100-150pips.