I agree with the most of replies here. The most effective way to become a good and ultimately professional trader is experience. And it means that not all the time you are on the positive side and gaining profit. It also includes losing at some point but that is where effective learning takes place. So take all the patience and practice and you are good to go.
Yeah, experience is one thing that we cannot rule out from any form of professionalism and the thing with trading is that you are just never going to stop learning no matter how professional you think you are as there are always new things to learn every single day.
Nevertheless with patience, more learning and studying, making of mistakes and learning from it, you are definitely going to keep being better at becoming a professional until you can gladly say to yourself over the years that you have learned more than enough.