i usually get confused that in which coin we should do trade and when... how can i understand market...

How to say about contracts, if you don't have your own thinking, the result will definitely be zero. With your own thinking, it might reach zero even faster. The hard work you put into watching the market is for making money. If the risk-reward ratio is not 1 to 3, I do not recommend you to open a position. My profit and loss is a few USD because I always defend and take profits at high points. Lastly, avoid contracts without a stop loss.