You speak of trend, but how can I evaluate it other than waiting for fluctuations of prices? What are the indexes to look after when monitoring trend changes?
you can evaluate the trend of anything you're holding, it is the fluctuation of that price over a certain time period will determine whether the trend is up or down at any moment or possibly undecided (consolidating)
call up anything, is it up or down? (at this moment in time)
at what level when its hit, would you say that the trend is potentially changing? bear in mind a trend doesn't just reverse. it doesn't just go in the opposite direction, it takes time.
when that level is hit, you get out
as for the overall market, the same is true. the index all depends on the instrument. TWTR falls under the communication sector which will also have a trend, and that sector within the NYSE, which has a trend
when choosing a stock, look for a stock rising (good relative strength), in a sector that's also rising (relative to overall market NYSE) which is also about to turn into an uptrend or already in an uptrend.
the weight of the market, can influence a sector, and the weight of the sector can influence the individual stock
don't think you have to wait years for these conditions to be met, markets and sectors are cyclical. they don't all go down at the same time, they don't all go up at the same time.
its also not a bad idea to be in cash sometimes.
PM me if you need to go through these in more detail. its quite straightforward just takes a bit of practice to instantly see where you are in a trend.