What 17 successful people wish they'd known about money in their 20s

Your 20s are far from simple ... especially when it comes to your finances. Even the some of the wealthiest, most successful people didn't escape this decade without making one (or several) money mistakes.

We asked a handful of self-made millionaires and billionaires, CEOs and entrepreneurs, and best-selling authors what they wish they'd known about money from the get-go.

Here's what they had to say:

SEE ALSO: The 11 smartest things to do with your money in your 20s

Have a cash cushion

John Paul DeJoria, cofounder of John Paul Mitchell Systems and Patrón tequila

"Before investing or starting a company, make sure you have enough money saved for at least six months to pay bills or anything else that might come up financially. It's important to have a cushion of six months financial back-up before you invest or if something doesn't work out in your favor."

Learn to manage your credit cards

Mark Cuban, billionaire entrepreneur, investor:

"[I wish I knew] that credit cards are the worst investment that you can make. That the money I save on interest by not having debt is better than any return I could possibly get by investing that money in the stock market. I thought I would be a stock-market genius. Until I wasn't.

"I should have paid off my cards every 30 days."

Skills are worth more than a job

Tim Ferriss, angel investor, best-selling author of "The 4-Hour Workweek":

"In your 20s, optimize for learning, not earning. Work directly under or with master dealmakers and acquire skills. This is particularly true for negotiating and hard skills, like coding.

"What would you rather have: $20,000 more per year in your 20s, leading to making $100,000 to $200,000 a year in your 30s, or a lower-paying job from 20 to 25 — but one like a real-world MBA you're paid for — leading to making millions in your 30s?

"It often comes down to prioritizing skill acquisition over immediate, post-college earning. McKinsey or Goldman can be seductive, but it's easy to get trapped in a 20-plus-year path of paying for a bloated lifestyle that is always a bit more expensive than the year before. Serfs can become self-made kings, but consultants tend to remain consultants. The only true job security is a superior skill set."