I understood 2 things till now.
Do not speculate as btc is volatile in case you cant afford a loss.
Buy only that much which you think can be sold and sell at the decided price which you thought at the time of buying insead of waiting for more price to rise.
You really cannot the price of bitcoin exactly no matter how experienced you are but there are several signs and indication when the price of coin rises .Yes bitcoin is really volatile but the price indicators can give us some clue on how the market will perform at certain times mainly during holiday season .For example is the price rise during December as most of the traders knew that the price would jump during Christmas but the bull run happened and everyone booked a good profit during that run.