Charts
A chart on its own doesn't tell you much, but looking at all the runners, price movement, history and activity can help you get an overall picture of what the market is doing. Not everyone uses charts, I'm more focused on the ladders but I find charts useful for judging the range a horse has and is likely to trade.
Although I don't do it myself, many traders record their trading screens and watch back later. When a trade goes wrong, it might be worth thinking about why you opened the trade and looking at what the other runners were doing at the time, see if you can find any patterns or overall trends for that meeting/day, such as favourites getting backed/drifting, etc.