In 2019, seven out of 10 (70%) American investors experienced some form of regret when it came to their investment strategy — with 35% saying they wish they'd invested more in the past year.
That's according to a recent Nerdwallet survey, which polled 2,018 U.S. adults, ages 18 and older, among whom 1,235 have money in investment accounts. In this case, an "investor" refers to anyone who's saving money that's exposed to the stock market, even if that's through a retirement plan, such as a 401(k).
Not putting away more money isn't the only reason people are kicking themselves over their 2019 investing decisions. Another 16% say they wish they'd invested more aggressively, followed by 15% who wish they'd made more trades in 2019.
If you, like more than a third of Nerdwallet's survey participants, also feel regret over not putting away more money in 2019, experts say you shouldn't be so hard on yourself. While growing your investments is a worthy goal, you can always use 2019 "as your motivation to do a better job in 2020," says Douglas Boneparth, president and founder of Bone Fide Wealth. "It's not what you didn't do. It's what you are going to do about it now."
Malik S. Lee, an Atlanta-based certified financial planner at Felton and Peel, agrees. Lee says you "shouldn't beat yourself up over chasing returns or trying to time the market." These traits "are great attributes if you like to gamble, not if you are a sound investor," he adds.
Experts say that deciding how much to invest is a highly individualized process.
"The answer to this question differs for everyone. I think one should focus more on their overall savings rate. What percentage of that they should invest, depends on their personal goals and risk tolerance," says Lee.
When Lee refers to your "savings rate," he's talking about all savings in general. "This includes cash reserves, retirement plans and after-tax brokerage accounts," Lee says.
When you're in your 20s and 30s, you ideally want to start out with a savings ratio of 10% to 15% of your gross income and work your way up, Lee explains. Of that 10% to 15%, you can decide how and where to save and invest it.
"You shouldn't invest in the market without first putting money aside for retirement and already have an emergency savings established," Ryan Marshall, a New Jersey-based certified financial planner, tells CNBC Make It.
While many advisors recommend saving at least 10% of your income for retirement, Marshall argues you should aim for 15%. "This 15% is based on your gross income, and so, if you make a $100,000 salary, you should invest at least 15% or $15,000 per year," he says.
Although 16% of participants wished they were more aggressive in their investing in 2019, experts say making overly bold money moves isn't for everyone — and has a lot to do with your risk tolerance and financial circumstances.
"If someone wants to be more aggressive, they should understand the potential downside," Marshall says. "There is no unicorn perfect investment out there. Each investment has an upside and downside. Investors need to understand what the downside of an aggressive portfolio looks like."
One way to figure out how aggressive you should be with your investments is "to complete a risk assessment questionnaire that will ask a series of questions to determine how you will react in a market downturn," says Lee. To test yourself, here's an investor profile quiz offered by brokerage firm Charles Schwab.
Second, you can determine how "risky" your portfolio should be based on your future cash flow needs, or how much money you'll need to get by, Lee explains. To determine your cash flow needs, Lee recommends sitting down with a financial advisor, who can help you to develop a comprehensive plan or cash-flow projection for the next five to 10 years.
Based on this cash-flow projection, you can decide whether you feel secure about your financial future and whether you're ready to get more aggressive with your investments, Lee says.
Finally, you should also consider how much time you have to reach whatever goal it is you're investing toward, Boneparth explains: "Typically, the longer the time frame, the more aggressive you can afford to be with your investments. However, personal risk tolerances should also be taken into account."
Trading stocks simply means to buy and sell them via a broker. Although 16% of American investors say they traded less than they'd of liked to in 2019, the act of trading stock is now more popular than ever.
Just as the decision regarding whether to invest aggressively is a highly personal one, determining if and when to trade your stock is entirely up to you — and has to do with understanding the ebbs and flows of the market.
"Hindsight is always 20/20" when it comes to the market, Marshall says.
And since "some economists were predicting a recession in 2019 that never came true," Marshall adds that fear also caused many investors to "act more conservatively."
As a result, they ended up "missing out on a huge market rally this year," Marshall says. Going forward, "investors should focus on the long-term goals of their money and less about the year-over-year performance."
Despite 2019 being a good year for investors, it's important to keep in mind that trading individual stocks generally isn't considered the smartest way to invest. Financial advisors usually suggest going with exchange-traded funds (ETFs), which are often thought of as safer than individual stocks since they're professionally managed, pooled investments that track an index of securities. As a result, they're a more diversified choice than individual stocks or bonds, making them a less risky instrument for investors.
Like this story? Subscribe to CNBC Make It on YouTube!