Overtrading

Taking too many trades only increase your brokerages and not your capital

Large Position 

Taking large position affects your psychology and if market goes against you then either it will be big loss or you will exit early

No Risk/Stop Loss

Always calculate risk before you take the trade . Exit the trade at stop loss and dont hope that trade will become positive

No Strategy

Trade with a single trading strategy and stick to it with discipline . Trading without strategy will never bring consistency