1) RSI comeback from an oversold / overbought area
When RSI got in an oversold area and then comeback, above 30 we are talking about a BUY (bullish) signal.
Vica versa for sell signals.

2) When RSI is in consolidation
There comes a time when RSI can't get through either the oversold either the overbought area. In this case RSI 50 acting as a dynamic support/resistance. An unusual signal, but used widely.

3) Az RSI breaks through 50
RSI could be used as a trendfollower indicator aswell. In this case a clear trend should be seen on chart when it got through 50. If RSI crosses 50 from above, its a sell signal, vica versa for long signal. This trading style is similar what I wrote at point ONE, with a difference that in this case we are concenrating on the trend. Reduced false signals and better performance.

4) Technical Analysis on RSI
RSI is really good with filtering-out noise so Technical Analysis often used on the histogram. We can draw trendlines, supports and resistances, recognising patterns aswell. With this technique we can filter-out more false signals and receive better signals combined with.