Well there's one thing that is very important...
And for real, newbies should pay attention to this...
There's a difference between bottom fishing a particular stock on a day it gets hammered for whatever reason, and bottom fishing for quality stocks when their sector gets hammered in a sector rotation.
This is when you add to a diversified portfolio.
Say you need an energy stock in your portfolio, you identify one of the best, and then when the whole sector falls out of favor and drops... that's when you buy your energy stock.
Do this over time across multiple sectors, because it takes time. When everyone hates retail, buy the best. Same with energy, healthcare, consumer staples, etc.
It takes time, sometimes sectors stay in favor for a year or more... but follow this formula, and as the years pass, your portfolio will outperform the S&P handsomely.
~vz