My path to FI:
Graduated college and started work as a W2 software developer in 1988 and retired a couple months ago just shy of my 59th birthday. Always followed the traditional advice -- max out the 401K and IRA and never touch them. I think I did target funds initially, but for at least the last 20 years I've been 100% S&P 500 Index fund to minimize fees and maximize diversification.
Saved up and bought my first house in Boston (Waltham) in 1993. Started moving around the USA to pursue higher-salary opportunities (Boston > S.F. > Houston > Chula Vista > San Diego > New Orleans). Always purchased my homes (never rented) and each home sale resulted in a healthy profit (some of which was lucky timing and location choices).
Found my 54-yo frugal software developer wife in Texas in 1999, who continues to work. Only child completed college several years ago.
I won't say what my exact retirement/net worth goal was (it was more than $1M, less than $5M), but I hit it this year and promptly submitted my resignation.
I found a robust online retirement planner that offers a 7-day free trial (WealthTrace) and, based on all my inputs (life expectancy of 90, investment holdings, expected monthly expenses, social security, market returns, inflation, etc.), we will never exhaust our savings and I probably could have retired even sooner.
So, following the traditional retirement investing advice, choosing a career in an in-demand field, and living within our means worked for us. However, I'm not sure it still works for somebody starting out today. Cost of living and housing are so much higher now, and wages haven't kept up. Very glad I got my start before things got really bad and was able to achieve my Financial Independence goal.
Oh, another thing I did was to make use of free personal finance tools (Mint until it went away, Monarch Money now, not free) to track expenses and root out waste. I never created a "budget" or put any restrictions on our discretionary spending, but these tools really help to root out waste. To this day I categorize every expense we incur -- drives my wife crazy. "What is this $50 charge to 'Spanx'?" "UGH. Just put it under Clothing!" "Ok."
Edit: Other than mortgages, I have always avoided debt. Have never had a car note, and drive my cars until they die. I never pay somebody to do something I can do myself. I still change my own oil, do all home repairs within my capabilities, and still do all my own landscaping (though I am considering letting the neighbor's boy take over in the summers -- landscaping a corner lot sucks in the summer in the deep south USA).