I base my trading on single systems as well as on consensus between systems

Thus, I constantly research new trading ideas. The ideas are based on pattern recognition, candlesticks, common indicators, proprietary indicators, chart patterns, ... 

Whenever I find a tradable system I add that to my repertoire, having yet another way to receive signals about trades to take. Each and every one of the systems are quite simple, and each and every one of the systems have proved profitable in the period I test them against. I always know that if I get a signal from a single system and trade that signal, statistically I would make a profit. I do also believe, and I have managed to test that to some extent, that if I select the stocks that get more than one signal on the upside, and few, if any, signals on the downside, I am more likely to make money on that trade than if going with one single system.

Trading based on many different systems keeps me in the market most of the time

If you trade a stock index, and are not a day trader, you need a system that triggers easily to enter the market frequently during the year. Even if you do, you are likely to lose compared to trading the market as a "buy and hold" market (since the market bursts rather then trends).

To enter the market more frequently than that lead me into trading single stocks instead of trading indexes. To do this I need to be able to scan many stocks against my trading ideas. There are a lot of technical analysis tools that can do that on defined trading systems so that was no problem. Scanning enough stocks lets me find a pretty diversified market, and thus being able to find stocks going upwards even if the market index is in a downtrend. Even so, if I would have had only one single system, I would still be likely to be out of the market during long times of the year, since I would need to have quite a complicated system to be able to do both bottom fishing, trading with the trend and trading within ranges (most systems only work well in one of those situations). The systems I have when scanning the market gives me signals for all of the above situations, and I also have a "voting" mechanism developed that gives me a rating based on which systems as well as how many systems said what on which stocks.

Most of my systems run with a modest chance of win, and also a modest chance of profit

That is, the winning percentage varies between 33-58% depending on which system we look at. The average profit in the systems, considering cost for commission and so is not great, but the number of consecutive losses are neither very high although some systems do run a double digit number of losses in a row.

I do use stop loss levels and look at profit targets, but they are not fixed

That is, as time passes I continue looking at the price pattern and might change both the stop loss level as well as the profit target. I very seldom enter trades based on "if the stock reaches x tomorrow, then enter the market (it would demand to much time spent looking at the stock market during day time and I am not day trading).