1. Which exchanges you use and why?
The most reliable CEX that I used to use for trading was Binance. I said was because there have been some issues with the SEC and things are not on the better side yet. Well if you are in the USA this should be a problem to look out for. If not, you are good with it although anything could happen at any time. Another reputable centralized exchange is Kucoin. Also, I heard about MEXC but I haven't tried it out yet. So you can choose any from them. Or if you want to choose DEXs, you can do that too.
2. Proces... so first you screen the coins, how? You get signals from somewhere? Where? Telegram groups? Is it reliable? You pay? After screening the coins then proceed to technical analysis or chart analysis? You do daily trading, scalping, swing... what is your method and why?
Never depend on signals or copy trading as a beginner. Learn the process on your own and do it on your own. This is important because if you become dependent on them, you are most likely to learn nothing about trading from them. You can use them to compare your analysis for better results and understanding.
And why pay those who know what is real or scam when you can do it on your own? When you are learning to trade, do the long trading. It will help you to understand the process as you are dealing with more data and time. Never go for quick money. Stick to your learning and strategy. If you follow this and keep working on your trading strategy, you can become a good trader. It takes time for sure but it is 100% worth it.