Quote from cgeorgan:
Limit orders: You need to model for price to trade through. Ensure that your software doesn't do a "one-touch" and fill you. This is important for both entries and exits (that will cover your slippage on limit orders).
Market orders: 1 tick of slippage every time. If it's a market entry and a market exit, that's 2 ticks total, per contract.
Stop orders: 1 tick of slippage each time. For live trading, you're best off using a stop-limit that has a limit of 10-15 ticks past your stop price (trust me). Yes, it sounds like stop-market, but that time you don't get filled is the time you really pay for it.
Backtesting is OK to start, but you need to forward test on live data for at least 3 months, better 6 months (I think a year is a lot if you're running the thing daily).
2 cents.
Great response, just what I was looking for. I have been testing limit orders and making sure price trades through so I have that part down. My only question left is slippage regarding reverse orders? Is there any benefit to using reverse orders when it comes to slippage?