1. With current situation what are the best coins we can use to day trade and long term trade ? to make a decent profit.
2. what is the best trading platform in your experience? or what is the platform you use for trading?
All the reputed exchanges for good platform for cryto trading. From the veteran platform of poloniex and bittrex, you may choose the latest addiction Binance also. Still, never leave your unused capital within exchange, withdraw them time to time and re-deposit whenever you need them again. Many incidents of exchange hacking had clearly stated that.
Market is always unpredictable. But, the continuous volatility of market ensures continuous opportunities of making big to decent returns for your capital and efforts. Yes, always be ready to put more efforts as much as you are able to. Because not all big capital traders are not making good profits but small capital traders with hard working are making big profits, as per I have observed.