3 things I wish I knew before I started investing, according to a personal finance writer

I started investing at the age of 20, shortly after graduating college and getting my first job. But for the most part, I was doing it entirely wrong. 

When I started investing, I was convinced that I needed to invest in individual stocks, putting a lot of thought into choosing the right ones and using an individual investment account (which wasn't the correct type of account for my goals). It didn't help that I started investing in late 2017 during one of the longest bull markets in American history, which was followed by dramatic volatility brought by the pandemic.

While I don't regret investing — doing something with my money was better for my financial goals than letting it sit idle, and I did learn from the process — I believe that I could have been savvier if I'd known several things from the start. 

If I could give my younger self a few pieces of investment advice, I'd focus on these three things to make my investing more consistent and less intimidating. Remember that these are my personal views, so you should consult a financial advisor to determine what strategy is best for your situation.

Starting out with an investing app, I was enticed to pick individual stocks and constantly monitor my investment account, as if it were a game. After all, many of the top investing apps like Robinhood and Webull make trading very easy by charging no commission to buy or sell stocks and allowing fractional trading.

I was convinced that investing had inherent emotional highs and lows and that the constant barrage of red and green tickers should dictate how I was feeling about my finances. I thought that someday I would eventually "win" at the stock market and that if I just fed it enough of my money, I could eventually strike it big. 

As I got more into writing about investing and personal finance, I realized how wrong this mentality was. And for the type of investing I focus on — building up a nest egg for later in life — stock market performance shouldn't be dictating how I feel about my finances or my future. 

I came to find that investing should actually be boring. It should be about setting aside an amount you can afford, investing in an index fund (an investment that tracks the larger market through a benchmark like the S&P 500 or the Nasdaq 100) or mutual fund (which pools money from investors to buy stocks and bonds), and largely forgetting about it. Riding the emotional ups and downs of investing was exhausting, and could have led me in a direction that would have put me farther from my goals.

Consider robo-advisors

Now, I've largely automated my investing. I've automated deposits from my checking account as a part of my budget and even automated investment decisions with a robo-advisor, a software that makes investment decisions for you based on your age, goals and how much risk you're willing to take. This software can be helpful for those of us who don't have the time or knowledge to invest the money ourselves. While there may be a fee involved, robo-advisors can help you make a balanced portfolio without much effort.

CNBC Select has reviewed several robo-advisors and ranked Betterment and Wealthfront as the top ones for their low barriers to entry, no trade or transfer fees and low 0.25% annual fees on the account's balance. Both apps also offer useful automated tax tools like tax-loss harvesting.

At the beginning of my investing journey, I generally found myself using individual taxable investment accounts. One of my biggest mistakes was overlooking retirement accounts.

Retirement accounts come with major tax advantages — many don't require you to pay taxes on the contributions or the money you earn until you withdraw the money in retirement. While they do have some restrictions on those withdrawals (you need to be age 59 and a half to take withdrawals from a 401(k) plan without a penalty, for example), the advantages can make them well worth it.

To be fair to myself, I didn't have access to a 401(k) plan until a few years into my career. While that's not an uncommon situation (only about 67% of private industry workers actually have access to one according to the U.S. Bureau of Labor Statistics), I know now that I could have been using other types of retirement accounts, such as a Roth IRA. With these accounts, anyone with an income below a certain amount can contribute up to a certain limit for tax-free growth. Some of our top picks for IRA accounts include Charles Schwab for its $0 minimum and access to expert investment advice, and Fidelity Investments' IRA for its customer support availability and no transaction fees for over 3,400 mutual funds.

Now that I understand the importance of retirement accounts, I make it a point to contribute to my 401(k) up to my employer's match and then invest in a Roth IRA up to the annual contribution limit (in 2023, that's up to $6,500, or $7,500 for those age 50 or older). If I still have leftover money to invest, then I'll consider an individual taxable account. 

When I started investing, I thought there was only one good time to invest: when the market was down. So, when my investing apps were flashing red, I came to see it as an opportunity I had to buy into. But, as I started to learn more about personal finance, I realized that wasn't the case. 

Over the course of my career, I've spent hundreds of hours on the phone with financial planners, people who have retired early, investing experts and even people who head household-name investment apps. One common refrain has made it into my own investing philosophy: It's not about timing the market, it's about time in the market. 

The idea behind this phrase is fundamental to a strategy called dollar-cost averaging, which states that investing regularly regardless of the market's state can even out the ups and downs over the long term. It's a strategy I've come to embrace on my journey to make investing as boring (read: effective) as possible. Another pro: it requires very little maintenance, especially when I'm able to set automatic investments to my accounts, as is the case with a 401(k). 

Now, I make an effort to invest as regularly as possible, regardless of what's in the headlines. While that type of thing would have swayed my investment decisions in the past, I don't think as much about it anymore. I know that for my style of investing and my goals, investing is less about when I invest and more about letting money ride the ups and downs for a longer time. Generally, I don't even pay attention to my investment account balances or the charts which have become increasingly chaotic in recent years — I'm relatively young and still have many years (read: time in the market) until I'll need the money I've invested. 

I really wish my 20-something self treated investing less like a game and instead focused on automatic investing and simplicity. I also wished I'd focused less on trying to time the market and focused more on the long time horizon I have in front of me, and contributed more to tax-advantaged retirement accounts. However, ultimately, I was extremely fortunate to be investing at all at this point in my life and I'm glad I learned these things eventually. It truly is better late than never.

Catch up on CNBC Select's in-depth coverage of credit cards, banking and money, and follow us on TikTok, Facebook, Instagram and Twitter to stay up to date