My single best financial move was when in 2008 (just before the Financial Crisis) I decided to invest every month a certain amount of my salary in a moderately risky ETF like Vanguard’s VOO or VIG: I did this no matter what and never touched this investment for a decade.
I also increased the monthly investment as soon as my career progressed so not to fall into the increased lifestyle trap like I observed my peers were doing.
This is admittedly a “boring” strategy than anybody can follow and does not require you to learn exotic options or get any insider information.
After I started a decade ago, also my mum, my little sister, my girlfriend, my old uncle and a few of my friends (all of them completely alien to any financial knowledge or investment experience) also took this (long-term) approach with excellent returns.