The MAC-Z line and signal line can be utilized in the same way as a oscillator, with the crossover between the two lines providing buy and sell signals. As with most crossover strategies, a buy signal comes when the shorter-term, more reactive line – in this case the MAC-Z line (blue line) crosses above the slower signal line (orange line). For example, when the MAC-Z line crosses below the signal line it provides a sell signal.
Zero line crossing
The zero cross strategy is based on either of the lines crossing the zero line. If the MAC-Z crosses the zero line from below, it is a signal for a possible new uptrend, while the MAC-Z crossing from above is a signal that a new downtrend may be starting. This is special powerful if the lines has a fast up or down movement but the price action doesn't reflect that movement.
and divergences is my favorite signals. When price action and oscillators follow the same path it is called Convergences, when they don’t, it’s called a Divergence. Don't confuse the two because they have not the same meaning. But be aware that for example during consolidation or low liquidity, some small divergences between price and indicators might form, but that doesn't mean we should consider them as real divergences.
There is many different types of divergences. It is easier to show a picture then explaining it so I recommend you to check out the link below. Especially the top image. It sums this up very well
The leader is only showing the crossing of as a vertical line