Discipline, most important. Other traits will automatically develop once you start trading with discipline.
Successful traders always avoid emotions, always formulate a trading plan and know when to enter and exit a trade. Apart from that , they maintain discipline and take time reviewing their trading activities/decisions , revisiting their past decisions and make new and effective strategies
Treat trading like a pinball game. It has a high degree of randomness and chance, but with practice you can hone an edge of knowing what and what not best to take. Losses happen, suck it up. Don't get beat up, you need to be a trading psychopath to this game, no feelings, just keep smackin' 'em.
One of the important traits of successful traders is the ability to make quick decisions and move fast when opportunities develop and still saying patient and doing very little while waiting for the trade to work. Often people have difficulty with this duality. They either act aggressively and stay in constant emotion or be so patient that inertia sets in.
Patience Discipline Learning from Mistake Accepting the defeat Money Management Knowledge in market's trends and conditions.
Successful traders know that their greatest enemy is their own emotional state and they understand just how dangerous it can be if they overreact and make quick decisions without thinking so a successful trader should be proactive and not reactive.