like a jag.

Trade a listed product. For currencies that is the CME. Use a broker that does not trade against you or sell your order flow. If your method will allow it use limit orders. Find out specifically how you broker handles limit orders. Forex is still the wild west and is an unregulated marketplace. Limit orders do not have standing, they are considered indications of interest until executed and that will NEVER favor you. Some brokers leave what would otherwise be marketable limit orders reside on an internal server NOT at an exchange or on a computer where counter parties will see them. Often once a limit is touched that order reverts to market so you have to know how your desk handles that and if there is a way to in effect enter limit price or nothing.

That said, when trading spot I use MB Trading and I can not remember ever having a real objectionable issue with slippage. Often I'd get price improvement with them through their ecn-like market place.

All the best and good luck.
Dan