Saving money is really hard. Whether it's covering an unexpected expense or realizing you spent more on your credit card last month than expected, having any money left at the end of the month should be cause for celebration. But once you finally have some cash saved up, then what?

Fool contributors Brian Withers and Brian Feroldi provide some advice on the Fool Live show, recorded on Jan. 14, that provide insights into how best to invest your hard-earned capital.

Brian Feroldi: OK. The biggest lesson that I learned from when I first started is this: Your capital is precious. Don't waste it on garbage.

When I first started investing, I was very attracted to garbage. I view garbage as two categories, in particular, really interested me in the beginning. Penny stocks. So stocks that were below $5 per share and high-dividend-yield stocks. I just pulled this from Finviz. These are companies that are over $10 billion in market cap and I just sorted by dividend yields.

I'm not calling these companies garbage. I'm sure there's a couple on there that will bounce back and do wonderful. All I can say is the old me, 15 years ago, if I had access to Finviz, this would have been my homework. Step 1, certified dividend yield, done. That would've been the homework process.

Obviously, I did very poorly because I didn't do any research up front and I was solely focused on short-term gains, and I thought that dividend yields and penny stocks were the best way to get there. A lesson learned the hard way -- your capital is precious. Buy quality businesses and avoid garbage.

Brian Withers: There you go. Excellent. All right. Well, another way to find quality companies, sometimes they're already in your portfolio. This is Amazon (NASDAQ:AMZN) [laughs] similar to Netflix. The slide thing is in the way, but this is 2005. I sold again about the same time I sold out of Netflix too. Luckily, I was smart enough to get back in, but these weren't huge positions for me.

What's interesting is, I always thought Amazon was too expensive. The valuation was just too much for what the stock was worth. Silly me, between this buy and this buy, I bought another 200 other positions, this one, 88 and another 256. So I had 450 chances [laughs] to buy Amazon again, and didn't do it.

I know we've talked in some of the other shows about getting excited about putting a new stock in your portfolio. Recently, I have been buying a lot of the same stocks that I own to increase the positions, and the joy you get by adding just that little bit much more to the stock that you already own isn't as exciting as adding a brand new shiny stock to your portfolio to track. But you know what? It can be tremendously more lucrative. There you go.

Feroldi: Well, just stop there because I want to congratulate you, actually. The fact that you went from owning something to not owning that thing, then watch the price go up and say, "I'm going to rebuy that thing that I sold last year for a lower price." That's super hard to do.

Withers: That is very hard, and that's why these boxes, which are the sold-out, are tough. They're sort of like "put them behind you and forget about them" kind of moves.

Feroldi: Yeah. But I think the point is completely valid. I do the same thing where I'm always focused on the new thing. A lot of that was because of just our roles at the Fools; we're paid to hunt around and find stuff, but 100% agree, a lot of times, the best stock you could buy is one that's already in your portfolio.

Withers: Yeah, and you know it, and hopefully you've had it for years and you understand it and you're more comfortable with it.

Feroldi: Totally.