I have always believed that a solid trading plan is essential for success. As traders we always want to be in the market and actively trading. Not trading is difficult to do, but a necessary skill to master for trading success.
Cash is a position, and is just as appropriate at times as being long or short the market.
Along with listing when you will place a trade, try adding a section to your trading plan outlining times when you will not trade. See if this helps reduce the number of losing trades you have.