I never buy a full position at once.....buy a few at say 5 then set a buy for maybe 4.60....etc to a point where I feel is a short term bottom. Also going the other way sell on a step by step basis unless news drives up the shares to a price I fell good about selling.
Because I mainly only buy/sell with stocks on my watch lists I pretty much know what to expect but not always.
For me...alot of my trades are what I just have a gut feeling on.
I am probably not as technical or fundamental as many here or in the markets.