Here's some wisdom from Jonathan Clements, an excellent financial author. Here's a top-level list of his ranking of financial decisions.
How much you borrow for college.
What career you pursue.
How early in life you start saving.
How big a house you buy relative to your income.
Whether you marry the right person. (I'd rephrase this to "Who you marry.")
How often you replace your car.
Whether you make a lifetime commitment to stocks.
Whether you have children. (I'd add "... and how many.")
Whether you waste time and money on the foolish pursuit of market-beating gains.
When you claim Social Security.
Here's a link to the full article. For more about Jonathan Clements and other personal finance authors click on Resources.
All the best, Tim