What should I focus on when evaluating a stock if I want to be somewhat conservative?

I recently read an article in Forbes titled "Investment Advice From The Vietnam Veteran Who Turned A 2-Bedroom House Into A $4.7 Billion Fortune" about Arte Moreno and his response to one of their questions made me curious:

Forbes: What assets are you buying in this environment?

Moreno: There are some stocks in the market right now I like. They get banged up, but I like the asset and you can average down if you look at it that way. Pretty much everything I deal with has some type of return on it; some kind of dividend. If you look back a year ago, we had very low interest rates, like zero. So when you're looking at a stock and not only do you really like the asset, but then they're giving you a dividend, it’s such a bonus. You're setting yourself up for potential stock growth, but you're also receiving 3% to 4% annually.

I really try to stay by the book: I like to buy companies at around 15 times price-to-earnings. I have a couple strong positions in Amazon (AMZN), Alphabet (GOOGL) and Apple (AAPL). I've been buying Apple forever; every time it goes down, I buy more Apple. I also buy JPMorgan (JPM), which pays about 3% dividend. Another company I really like, and have been invested in for a long time, is Blackstone (BX). The multiple doesn’t fit in there because it's high, but I just like their whole portfolio of assets.

I’m really pretty good about keeping diversified. But I really look at stocks that give you a good dividend. I look at a company that's not generating any cash, has no dividend and has this crazy high PE multiple, and I just stay away. I think it's for other people. It's not for me.

He considers himself a fairly conservative and by the book investor, so I was interested in learning more about how you guys evaluate a stock and what you think of his approach.

For example, one stock that I've been looking at off and on for quite a while now, but don't own, is POSCO (PKX). They're currently at a 9.32 PE, which is below the 15x that Arte Moreno looks for, but they have a 3.90% dividend and they're generating cash. Is that info enough to make an investment or do you look for more?

Thank you for any help you can provide. I'm genuinely interested in learning more about investing. I have a couple funds for retirement, but I was considering adding another account at Vanguard to invest in maybe 4-5 companies I like once I learn more.