In last week's episode of Rule Breaker Investing, after sharing his seven principles of success for long-term investing, David Gardner put the call out for listeners to submit their own.

In this clip, the Motley Fool co-founder reads a few of his favorite submissions. Listen to hear about the fees you have to know about when managing your 401(k), how to make decisions without being led by fear, how much buzz you really need to hear about an investment, one metric that can be used to guide you toward less risky picks, and more.

A transcript follows the video.

This podcast was recorded on Nov. 4, 2015. 

David Gardner: Last week, as you'll recall, we talked about seven principles for investors, seven principles for those who do what we do for the long term -- that is, we risk some capital, and we pick carefully. We put a lot of effort in on the front end, before we make a decision, and then we usually just let it go, a lot of the time. Just, in the best Frozen terms, we just let them go. And indeed, those are many of our best picks, the ones that we just allowed to grow over time. But I asked at the end of that podcast, I bet you have some principles. I've given you seven. What's your eighth? And I just wanted to share back at the start of this week's podcast some of my favorites, some of the ones that I've seen over the last week, in no particular order. 

Scott answered, "Eighth principle, simple. Two words," he wrote, "Fees matter." That's Scott, who's @Golfer17059 on Twitter. And Scott, boy, do I agree with that. It's a wonder to me how few people realize what they are paying for their financial management every year. A lot of people just check that box on their 401(k) plan, select a few funds, don't really realize the fees that they're paying their funds. If you've got a good 401(k) plan, I hope you have a good choice of funds, all of which should have low fees. It's called the expense ratio, the amount of money taken out of your holding each year as a percentage of what you hold. So, for example, if you have $10,000 in your 401(k) plan, and your fund manager took out $100 from that, that would be a 1% expense ratio. A lot of Americans don't even know what fees they're paying in their funds, don't know what an expense ratio is. It couldn't be simpler math, again, just how much you paid them as a percentage of how much you have each year. Fees matter. Fees matter a great deal.

Next one up, Tobin Anthony, @TobinAnthony on Twitter. Tobin wrote: "A lot of times, boring is better than buzz. May not get the same press as the hot ones, but will produce." That was Tobin's eighth principle, and here again, I agree. That's why I'm reading it on air. Good job, Tobin! Back in the early Motley Fool days, we actually had a portfolio, one of those free online portfolios, back primarily when we were just an AOL site. It was called The Boring Portfolio, and the whole style and strategy of that portfolio -- which was a good one -- was to intentionally select incredibly boring companies. 

Now, I don't specifically target boring, but I have a lot of boring on both my Stock Advisor and Rule Breakers scorecards. Companies that just have acronyms as their name, like TDG, which is actually TransDigm Industries, but those kinds of companies. Or just ones that, what they do isn't that exciting. How about FactSet Research Systems (NYSE: FDS)? That's a pick from 2009, still an active pick today in Rule Breakers, a company that really just oversees lots of data, sometimes gets quoted in different financial articles. You'll see them opining about earnings, or they're keeping track of all the analysts. They're all about research and data. Very boring company. We recommended it at $52; it's about $175 today. Boring triple over the course of the last six to seven years. Casey's General Stores (NASDAQ: CASY) is a recent pick I made in Motley Fool Stock Advisor -- that's a pretty boring company. It's convenience stores in the Middle West. It doesn't sound like 3D printing or the next magic thing, but it's been a wonderful stock, not just in the months we've had it, but really in the decade or so leading up, and I think in the next decade. So, boring. I like boring.

Next one up, I'd like to highlight Junto Financial, @JuntoFinancial on Twitter. Eighth principle: "Always other fish in the sea. Don't cry over missing the big one." And I agree with that as well. Warren Buffett talks about how every time a stock comes down your pipe, it's like a pitch. It's like you're playing baseball and it's pitched at you. And you don't have to swing. We don't have to swing every single time. And if we didn't swing and it was a beautiful pitch, we shouldn't spend too much time worrying about that going forward. A, right away, the good news is this isn't baseball. You can go ahead and buy it even though you didn't have it the first time around, or believe at first. Or, you could just not sweat that one, because there's so many good stocks out there, and there are new companies becoming public, some great businesses being born all the time. So I agree.

I'm having fun, so I'm going to go with a few more here. Jason Newman, who I had an opportunity to highlight briefly last podcast, his 90-stock portfolio that he's built up over time using Motley Fool services, and all the success he's had, and he said his eighth principle is: "Be sure to share the experience with others." And I know Jason's not just a good guy and a good Fool, but a father, among other things, as well. A lot of us are parents; that's a clear way that we can share. But friends, co-workers. Thanksgiving is coming up here in the United States of America. You've got a lot of opportunity to share it out, and that says such a beautiful point. Oh, and by the way, Jason's Twitter handle is @JNew4. You can follow all these wonderful Fools if you like. We do.

Matt Maurer, @Maurerpowerin, wrote, rule No. 8, for him, it's "Fear-driven actions are almost always wrong. Flee a burning building, but the building has to actually be on fire." A lot is said about fear and greed in the market, words I don't really like to use, because they're kind of negative. I prefer, instead of fear, I like caution. And instead of greed, I like opportunity. But you're right, you're absolutely right, Matt, that a lot of our worst mistakes are made -- not just with money, but often in life -- driven by fear, and in my experience, anyway, fear is often just because somebody doesn't know, wasn't taught, doesn't understand. As I've sometimes been wont to do in speeches I've given over the years, I'll ask, when medieval mapmakers hadn't been to a place, what did they write in that corner of their maps? They would write, "There be dragons." They didn't write, "I don't know, no one's ever gone there." No. The thing they didn't know, that they hadn't explored, was a fearful thing to them. "There be dragons." And we do "there be dragons" a lot, especially if we're new to investing or we don't understand the money world, it seems scary, and we make some bad decisions.

All right, one more. Deborah Gray, one of my favorite Fools, a longtime Motley Fool member and now staffer, one of those people who've risen through the ranks of our community to become part of our team and our staff here at The Motley Fool. Deborah wrote, rule No. 8, "Pick companies that you want to learn more about." And there, too, again, boy do I agree. One of the best ways to invest successfully over long periods of time is to ensure that you enjoy the process. And one of the best ways to ensure that you enjoy the process is to pick companies that fascinate you. It might be that you work in that industry, or it's your favorite hobby, or it might be just that it's an interesting new frontier, something that, as an intellectually curious person, you'd like to know more about. 

I've often heard it said that everything we encounter over the course of our day or our lives either slightly attracts us or repels us, sometimes more than slightly. But we're either attracted or repelled by what we're encountering on a regular basis, and when it comes to your stock market portfolio, I hope that you're attracted and you pick stocks that give you energy, don't sap energy, as you become a part owner and follow them over a course of time. One of the things that we do at The Motley Fool is, we've created risk ratings. I'll talk about that in another podcast, but we've actually put a number on each stock that we cover that estimates its risk, the risk of holding it, the risk of losing quite a bit of money in that particular holding versus any other holding. And one of the questions we ask in our risk rating is, in so many words, what Deborah's just said -- it's, "Will you enjoy following this company?" It's actually about you, not about the stock, which shows us that risk is often subjective. It's not just an object of thing outside of you. You participate in this. If you enjoy following something, it's less risky for you, because you're going to be learning, knowing, interested in it. If you're taking somebody else's tip, it's a company you don't really know about but it sounds like a hot technology, and you're not really following it, that's riskier for you than it would be for me, if I were opposite. 

All right, so, really fun, and I'm going to do that in future podcasts. I enjoy asking our community. Those Fools who are listening in every week, I enjoyed asking you things, because you teach me a lot, and I like to share it back, which is what I just did.

David Gardner has no position in any stocks mentioned. The Motley Fool owns shares of and recommends Casey's General Stores, TransDigm Group, and Twitter. The Motley Fool recommends FactSet Research Systems. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.