I'm going to assume you're talking about trading equities, and trading on a longer timeframe than just intraday. First, your experience in buying into strength is not unusual. Has never worked for me. The reason you read to much about the strategy is that people who made big money in the last major bull run prior to 2000 are still hawking the strategy years later. And the sad part is that people are still buying the books. But the past 3 years we've had a trading range that's been perfect for entering weakness at the right time, on the right stocks. But buying into weakness can be consistently profitable if you understand the logic of why a stock is falling, and when it is safe to enter. Nearly all stocks, for a variety of reasons, undergo periods of heavy distribution and rapid decline, if only for a few days. Think about what's happening there. Watch it happen. Understand the process. Focus on solid companies with good core fundamentals, because they will attract new buyers. When the selling has climaxed, that's your entry point. Your ideal trade will be in a company for which there is no particular bad news, or which may have been brought down with a sector. The overall market will also set up a lot of these trades during periods of weakness. Don't trade drug stocks, or any stock that can be impacted by regulatory issues. Hold for a reasonable profit. Rinse and repeat. And stay diversified. Don't hang yourself with too much in a single position. Hit singles and doubles, again and again. Good luck.
After a selling climax: buy on the way up and sell higher. After a buying climax: buy on the way down and sell lower. Use strict money management. Use stops to enter / reverse / exit. I prefer options: buy premium / verticals.
Yeah, I am trading stocks, no day trading. I stay in the position until it hits my target or until my options expire. I try to buy options that have at least 20 days left to expiration. I haven't tested my strategy on futures yet. I also haven't been using any fundamentals. I might try to see if I can improve my strategy some with fundamentals, its a lot harder to back test. I limit my risk to around 2% per position.