Slightly tells me that I know bitcoin from this forum around June 2017,
But I haven't kept up with the crypto world for a long time due to my busy business and boredom with the price of BTC in 2019.
So I almost forgot all my assets until there was one. the thing I think is my stupidity, I omitted my Trezor which still contained around 9 ETH at the time I bought ETH around $ 700 in mid 2018, and ETH keeps dropping so I ignore it.
Long story short I want to start from scratch I want to ask the seniors who are here.
I want to start trading again. Could you please give me some advice so that I don't go through things like a few years ago.
You have already huge profit from your 9 ETH but you should find a way to recover it. Don't waste it, the value of Ethereum is almost 5 time of your capital that time you bought your Ethereum. I believe you will still recover it as long as you have your password and private key in your Trezor wallet. If you recover it, then you can continue investing in crypto and start trading, just learn first about it.