I went down the rabbit hole a little deeper than expected and accidentally become an expert in this field. In my theory of personal finance, I divide it into 3 levels. 

level 1

This is not a complete list, just whatever on the to of my head but I can show you a rundown of Dave

Dave Ramsey Principle

• Have a Monthly Budget

• Spend Less Than You Make

• Stay Out of Debt

• Save and invest money

• Be outrageously generous

Dave Ramsey 7 baby steps

1. Save $1,000

2. Pay off your debt

3. Build emergency fund: 3-6 months of expense

4. Invest 15% of Your Income

5. Save for your children college fund

6. Pay off the house

7. Build Wealth and Give Generously

Dave Ramsey Advice

• Buy used reliable car in CASH

• NEVER give loan to family and friends. If you want to help them, just give them the money and don't ask to be paid back.

• There is no WE if you're not married. Don't go buy a house and create a mess at break up.

• Invest order is 401k match, Roth IRA, then 401k again

Dave Ramsey Critics

• Absolute no debt which includes no credit card debt. Most people would disagree with not using credit cards in a credit base economy.

• 15 years fixed rate mortgage is very hard to achieve, especially in high cost of living areas.

• Invest order may not make sense for FIRE people

• Invest portfolio is 4 mutual funds which is against the long term passive investing style of index fund

level 2

*Here I want to really stress out about diversification because Bogle includes bond which is a very niche thing compare to other investors. At first, I didn't really get it until I watch a MIT lecture on Youtube about Portfolio Management and actually see Prof. Jake Xia do the math on asset risk-return and their correlation factor. The math is complicated but long lecture short is that diversification only matters if the correlation between 2 assets is as close to 0 as possible. It sounds normal and obvious now but definitely was an enlightenment moment for me at 19 years old and actually understand diversification mathematically, not just abstract idea of the eggs and the basket. Anyway, back to the three-fund index portfolio, there is as little as possible correlation between US stocks, bonds, and international stocks. If the US goes wrong, only bonds and US stocks are affected, you still have international stocks. If there's a global crisis, both domestic and international stocks may go down but you still have bonds. If the economy is going well, bonds and international may not profit much but US stocks will profit a lot and push your portfolio up.

Bogleheads Critics

• Too safe, if you are in your young 20s and have 40 years ahead in the market, you can afford more risk

• Easily underperform in Bull market

Further Resource

Well, there's a lot more in this level and I can't show them all here but I can give you a list of resource in case you are interested.

• New Money Youtube channel. Long term passive investing style. This one fits my investing style the most. They do a lot of analysis of Warren Buffett, Charlie Munger, Bogleheads, and other big investors. 

• Minority Mindset Youtube channel. Cash flow investing style. Fit best if you like cash flow. Also, he covers recent market trends with very logical reasoning. Downside is cover market trend. There's no point if you are a long term investor

• Million Made Easy Youtube Channel. Long term technical analysis for the S&P 500. I used to run a similar analysis but he did a way better job than me. His analysis is best to answer the question of how much money do you need to invest monthly to get to your financial goal in the next 20+ years. Downside is too technical and content is boring after 5 videos.

• Financial Order of Operations (FOO). This comes from the money guys show on Youtube. They are among the most reasonable financial advisors that I know. They are not extreme debt oriented like Dave Ramsey or too conservative like Bogleheads or too much active style (single stock) like Warren Buffett. Probably the most balanced people I know. Downside is too much focus on retirement (25% of income) and I disagree with their car loan guidelines (you should pay CASH for your used reliable car) 

level 3