Did you mean to have good psychology in trading? To have it , i think we not need to do meditation. We should be keep learn and learn to more to understanding price action and to know all risk of trading, and we should be minimize the risk by make risk management . I dont see any relation between trading and meditation.
Honestly, having a good psychology when it comes to trading is not even something anyone can do if the mentality they bring into trading at first is not right. No matter how you want to meditate, if you approach trading as gambling, you have no strategy, you have no knowledge, you have no confidence since you have no skills at all, there is no amount of meditation that will actually make you successful at trading.
As far as I am concerned, the best way to trade is to build confidence in yourself, and the best way to build confidence, is to make sure that you have learned enough and you have been able to back test your strategy to see you are good to go. Meditation will not get all of that done for you the last time I checked.
When you want to trade, there is always that thing to at least find some peace within you first but there is no way you can find that peace if all you are after is gambling your position in the market without knowledge and like you said, it will not even get you far, before you will realize that no matter how you meditate without knowledge of what you are doing, you are just busy meditating for nothing.
Rather than meditating, every day, before I hit the market, I take my time to study it, wait for a perfect position to enter based on my strategy, and then make the best of it. That is my own meditation based on my knowledge, anyone who does not have a strategy and thinking meditation will help them out should go ahead, as I will love to see where that leads them.
We all know what is actually useful for controlling emotions of traders, it is knowledge, practice and experience, not meditation. I am not saying you cannot meditate before you trade as that is your own call, but what would actually make you to trade like a pro, is not meditation, but the confidence in your own self and in your strategy you have been consistently used to over time. Being a successful trader is about how you get to develop your skills and strategy over time and meditation is never a criterion to being a successful trader. You will be in a clear mind when you know what you are doing.