You should have some amount of money and select good exchanges with high volume. Then you study the trend of specific coins you want to trade in, and also learn and take advice from the experienced traders.
A good trader can use several exchanges and be aware of changes on them always. he is constantly monitoring the market and spends most of his time studying cryptocurrencies. He takes losses and lessons.
That's not a good trader, he simply do arbitrage trade. Looking for a cheaper token and asap sell in on other exchange which has higher price.
To become a good trader you need a few years, while showing stable results, because the investment is not a sprint, but a marathon and very rarely you can get everything at once
Not really, you don't need years to become an expert in something. We ever heard if we must learn for 10k hours before we can master it.