On pull-backs you can use Fib levels to see which one has the greatest chance. I have annotated the charts from TC Platinum version. Be sure to use the close prices not the open unless you are day trading in which case you should use moving VWAP and perhaps MA's.
If you are looking to go long a continuing trend, try to wait for a correction that is short and sharp and forms a well delineated V! It should literally look like that and about the same angle or a little less! As the price nears and peaks above the 78.6 line, be careful and make sure to look at close or if you are buying intraday, the 78.6 is NOT the price trigger! The price trigger is when it gets above it and continues. I like to put my buy up near prior lows of the correction start....Have fun with the toys! I will write more on where to place your buy trigger later! For more on this technique see Derrik Hobbs's work. Dave Landry has dubbed this pattern the Gatekeeper as so many corrections fail here and turn south.