Trading in coinbase oftens incur high fees. If you intend to day trade on a daily basis, you can try exchanges such as Bittrex that support USDT. USDT is a crypto coins that is pledged to USD price.
For day trding it is much more important to you must have good expeeirnce in day trading. because there is a big different between day trading and long term trading. In day trading you must have a good decision powerm so that you can take a quick decision, you must remain as active, you must study the market on regualr baases and you also need to chose such exchgane for day trading where the transaction fee is not so high, becasue you have take more than 1 transaction everyday, therefore its important to use such exchanges where the fee is reasonale.