Best way to identify trend for beginners

How can one be called a qualified trader?

How to determine whether your trading style is short-term or long-term?

I have been unable to set the stop loss in the transaction, how can I do a good stop loss?

How to understand the phrase "the simpler the trading system, the better"?

What is the degree of simplicity here? Or the simplicity here is not what I thought, just use a few indicators, so what do you think of this sentence?

I have had a few positions liquidated recently, but fortunately the losses were not very large. I would like to ask everyone, is there any way to prevent liquidation? Is there any trading discipline?