There are thousands of trading systems available these days. People is simply overwhelmed by the sheer number available and do not know where to start, who to trust, where to learn etc.
I have only limited knowledge of the trading systems available but I wanted to give my view on 3 that I know - Decipher's MACD-H (a.k.a. 4R1G or 4G1R) trading system, Dr. Elder's Triple Screen system and the system that I am currently using.
My general view on trading system is that:
(1) It should be simple and easy
It has to be simple and easy to use. I believe in simplicity and less is more. If you have a screen so cluttered with so many indicators and trend lines, you are only going to confuse yourself. Dr. Elder talked about "5 bullets to a clip". He uses two moving averages, an envelope, MACD lines with MACD histogram and Force Index.
(2) all the indicators should come together and complement each other
You need to understand how the indicators work together and complement each other. I have seen people trading with systems which has all oscillators and no trend-following indicators. You need to understand that both oscillators and trend-following (or lagging) indicators have their places and purpose. Indicators are easy to use but often abused.
(3) it should suit your trading styleLastly and most importantly, you need to understand when and when not to use a trading system. We are basically talking about market direction here. Most systems available today works well in a trending market. You need to identify the market direction before applying the trading system you have in mind. Bear in mind though that market trends only 20% of the time. Most of the time, it is in "random walk". So, the trend is your friend but he is only a fair-weathered friend.