The most important rule of trading is: play great defense, not great offense. Every day I assume every position I have is wrong.
I look for a 5:1 reward-to-risk ratio. If I think I can make five dollars for every one dollar I risk, I will take the trade. If not, I pass.
Don't focus on making money. Focus on protecting what you have. The money will take care of itself if you manage the downside.
Every day I start by asking: what could go wrong? Not what could go right. That question has kept me alive in markets for forty years.
The market is going to do what it is going to do. Your job is to position correctly before it does it, then get out of the way.
Losers average losers. Never add to a losing position. It is the single most reliable path to disaster.