Technical analysis is my tool of choice when it comes evaluating the direction of the stock market. I was a stockbroker in my early years and I completely dismissed the notion of drawing lines on a chart to determine market direction. I was wrong and, well, the discipline has also evolved to a great degree since then.
The basic premise of technical analysis is to use price and underlying market features to best determine what the investment (market) is likely to do next. I caution that we try not to predict, but rather let the market establish itself and move with it. Which gives the commonly heard phrase: "the trend is your friend"
The two most common price movements are trends and trading ranges. Trends are pretty easy to see. Bull market trends look like a gradual uphill climb. Bear trends look like a cliff you are about to repel down. Indicators for these are good at showing the momentum of move which helps with duration. The question is when do they begin and end. Ironically, bull markets are a little more difficult to see beginning but are easy to see ending. Although, the final moments can be drawn out because of the bias to be long the market. Conversely, bear market are easy to see beginning and more difficult to see finishing.
Trading ranges can typically start or end a bull market, although the do sometimes happen in the middle of the move when the market is really grasping for direction. The trading range itself is a back and forth between bulls and bears trying to determine the future direction of the market. The most common forms of trading range formations are horizontal, denoted with support and resistance lines and triangles which are non-uniform moves between bulls and bears. Some of these include ascending, descending and symmetrical.
The other factor of the technical analysis are time horizons. Markets move in patterns in short, intermediate and long time frames. The key here is to know which pattern has precedent. Almost without exception the longer time frame takes priority over the shorter time frame. So a pattern on a weekly chart would super cede that of a daily chart. If the short term charts pattern differs from the longer term chart this is typically characterized as a counter trend move.
The big difference is the advent of the underlying metrics use to identify the strength of all these pricing moves. Most trading and technical analysis websites have the available patterns for people to follow, but it is the application of the metric to the chart pattern that is important. You use different metrics for different types of charts (markets). One of the key reasons technical "doesn't work" for some people is that they look for one catch all tool for every possible market scenario. It simply does not exist. The other reason technical analysis does not work is that you may have good information but you still have to make a decision. Overall people tend to take a lot of other factors into account when making decisions instead of just evaluating what the market is telling them.