Hi, 27 year old, posting here. Because my best friend told me to start a Discover HYSA account. Also to open up a brokerage stock account such as Etrade. Invest into S&P 500 index funds, wire 500 dollars into etrade. He was telling me to invest 90% of my paycheck, keep 10% in emergency. And to put everything in Discover. And to max out Roth IRA. Says Etrade is never to be touched. HYSA is where liquid cash is stored. Money can be moved in and out. And to hold index funds should be held forever.

I'm new to mostly investing. I usually save my money. I would like to know if this is a good plan. Any advices or resources anyone can recommend?