Basics of Trend Lines

Trendline that has been tested or touched multiple times is more significant than one that has been tested fewer times.
Trendlines gain validity each time they are successfully tested.
A trendline with a lower slope will be more valid than one with a steeper angle.
A trendline that has lasted many years is more valid than one that has lasted a few weeks or months.
Trend lines should be drawn through the lows of an up-trend — and through the highs of a down-trend.
Draw trend lines through closing prices on long-term charts.
Use either normal or log scale charts but be aware of their respective weaknesses.
Trend lines must be respected by at least three lows (or highs in a down-trend) — if repeated twice, the trend line is not yet confirmed;
Trend lines should not intersect price at any point on the chart if extended.