Take profit? - cut lose? - market direction anticipation?

When to take profit? Take profit quickly or be patient to hold more time for more profit? When to cut lose? Cut lose earlier at maybe 0.618 retracement, or at the low of the breakout bar, or at the support (e.g. 50MA, 200MA, or previous low)? What if a stock bounce immediately after cut lose? Trading is an art and also dependent on probability. I think there is no fixed answer to these questions or any others. The answer is more likely related to the natural of the stock and the market condition.

Today market tanked for around 2%. I am also an victim of this sell off. In the past year, I am doing really bad at the market transitions from bull to bear. I am quite bullish these days. I thought the market would pull back a little bit to 50SMA then resume uptrend. My argument was the small cap (IWM) and micro cap (IWC) show more strength comparing to SPY and QQQ. There were still many good setup, especially in small cap biotechnology stocks. Because of this conviction, I still buy momentum stocks. However, there were no follow through in most of these stocks and reversed back. I cut loss in many trades today.

AERI: no follow through. I bought dip at the yesterday b/o level, but price went down further.

TGTX: initial b/o above 17, failed b/o. This stock sucks. I got whipsawed in it three times now!

ONDK: new IPO. failed b/o, closed below the b/o bar.

DATA: good fundamental stock. No follow through from yesterday's reversal. dipped below 83.8 which is yesterday's low, then reverse and closed high around 84.74. This stock still has a lot of dip buyers.

OVAS: gave up 4% gain. it only has around 200k daily volume. lesson learned: for thinly traded stock, take profit when there is good profit. Do not be greedy. I had a maximum 6% gain intraday.

NLNK: no follow through from yesterday's b/o. closed below 42. an inside bar.

NOAH: no follow through. Stopped out with a profit.

BMRN: very volatile intraday. hope it will b/o tomorrow above 94.

I shorted the market on Dec-31-2014. Market gapped up big on Jan-02-2015 then faded. My short did not work. My initial plan was that market had a gap down then I would cover. Today I anticipated market gap up but it gapped down and down 1.8%. Wishes not work.