"Rules of thumb can be a good approximate guideline for decisions, and there are tons of money rules that aim to get your finances on track. While everyone's situation is different, these serve as a good starting point.

We thought we'd put together a list of some solid, useful rules of thumb to follow. However, since everyone's situation is different, we've also included some scenarios in which these rules are worth reworking to your needs.

Budgeting

The 50/30/20 Rule

This is a popular rule for breaking down your budget. The 50-30-20 rule puts 50 percent of your income toward necessities, like housing and bills. Twenty percent should then go toward financial goals, like paying off debt or saving for retirement. Finally, thirty percent of your income can be allocated to wants, like dining or entertainment.

There are also variations to this rule, like the 80-20 rule, in which you use 20 percent of your income for financial goals, then spend 80 percent on everything else.

Why It Works: If you're not sure where to start with a budget, breaking it up into these basic categories can be really helpful. Those percentages help create a balance between obligations, goals and splurges.

When It Doesn't: You might have trouble with this if you have a hard time separating needs from wants, even with something like housing. If you live in a low-cost area, 50 percent toward housing and bills might be a lot. On the other hand, if you're not earning much, you might not have the luxury of only spending half your income on necessities.

These rules of thumb are good starting points for your spending. But maybe you want to adjust them, or make a budget that's more tailored to your situation. In that case, start from scratch, follow a few budgeting steps and design something that works best for you.

Buying a Vehicle

The 20/4/10 rule

When buying a car, you should put down at least 20 percent. You should finance the car for no more than four years and spend no more than ten percent of your gross income on transportation costs.

Why It Works: It keeps you from buying more vehicle than you can afford. It also takes your ongoing budget into consideration by calculating total transportation costs. These costs include not only your car payment, but also your gas and insurance, which can vary by vehicle type.

When It Doesn't: Depending on your situation, these numbers might not be realistic for you. For example, you may have a long, gas-guzzling commute at a low-paying job, making your transportation costs more than 10 percent. On the other hand, if you've got the cash, you might choose to pay for your car upfront rather than take on a loan with interest. In that case, the rule wouldn't apply to you."