Quote from WinstonTJ:
McGene - You need to tell us what you are trading (stocks, options, forex, futures, etc.). Also as stated above, this is VERY important... Are you factoring in fees AND spreads? Are you sending market or limit orders? Are you backtesting based on PRINTS or based on Lev2 book? Do you have size or just Bid/Print/Ask? Are you trying to provide liquidity? If so are you waiting for the print/price to move through your price or just assuming you got a fill at your price? If you are sending MKT are you adding a few cents per fill assuming someone is going to hold you there and screw you over?
Backtesting should be done very pessimistically. If possible back test time periods that you have run live (not 100shs, run fully live) your strategy and play around until you know where the approx 1:1 backtest to real life is (for that day) and set your backtest even more against you over a longer time frame.
Seems like if you have 1-2 entry conditions that go against you it may be something as simple as a stop loss? Do you have profit targets with trail stops or just trail stop from the getgo? How many variables do you have?
Sorry for so many questions - that was just a quick "off the cuff" ramble about the basics.
Good luck-