The guys at Ivyvest do a pretty good primer.
Here's an important consideration: the actual value of a company has nothing to do with the worth of a company, at least in the near-term. The market is interested in the spread between what the market thinks and what the stock actually does at earnings. One of my most seminal experiences was talking to a friend at RealNetworks back in 2002. I asked him how his stock was doing. He said "It's amazing. We're the only profitable dot-com left. We posted a thirteen-cent-per share dividend. We beat our estimates by twenty percent. But because Moody's predicted we'd beat our estimates by thirty percent, our stock took an eight percent hit yesterday."
Now - long-term, RealNetworks wasn't a good bet. His particular group was building mobile RealNetworks codecs for Symbian, a dead-end if ever there was one (he runs a boutique app development studio now). But you woulda been grand at RealNetworks from 2002-2007. Except since the Market decided RealNetworks was done, RealNetworks was done.
Google, Netflix, Tesla and Blizzard are often described as cult stocks - as in, properties that are desired and traded far above valuation by people who don't understand stocks but sure think Elon Musk is cool. Money can definitely be made on cult stocks, and Netflix has certainly evolved out of the space... but the important thing to remember is that when you're betting on a moon-shot like that, your only safe move is buy and hold. As David Rosenberg at Gluskin Sheff likes to say, "it isn't timing the market, it's time in the market."
There are two types of gains to be had in the market: alpha gains and beta gains. If you look at a stock, its calculated "beta" is right there; that's a coefficient where the amount over "1" indicates the volatility of the stock. Basically, if a stock has a beta of 1 it will make money in direct correlation to stock market rises. Since no one would participate in the market if it didn't make money long-term, you can safely predict that beta gains will come to you unless you fuck around messing up your portfolio like a crazed day-trader.
Alpha gains are why you mess up your portfolio like a crazed day-trader. Alpha gains mean that the stock's gain outperforms the market. Since the market is a closed ecosystem, for any stock to gain a dollar, other stocks have to lose a dollar. Beta gains are positive-sum. Alpha gains are zero-sum. And in a zero-sum gain, you will be beaten by those with insider trading knowledge, dark pools, arbitrage opportunities and other advantages that will never be available to you.
Full disclosure: I bet 100% of my portfolio in emerging markets in 2004 and crushed the market. Then I shoveled all of my money in indexed annuities in 2008 and crushed the market again. My wife's portfolio is also in an indexed annuity, except for the $20k we left at Prudential because why not, and all that money is in mutual funds. It crushed the market. Now - I'm not stupid enough to think I have some magical skill with stocks; my play is basically "macro paranoia". I am not a wise investor. Follow my advice at your peril. But also recognize that my experience flies directly in the face of all this "ETF! ETF! RAH RAH RAH!" bullshit that every fuckin' stock picker on the planet is pushing. An ETF is basically just another kind of derivative... and while ETFs are hella safer than the CDOs that nuked the economy in 2008, buying GLD isn't buying a safer form of gold, it's buying gold through ETrade.
We were going to get away from my financial planner. I wasn't entirely happy in my annuities because they're sketchy. But you know what? I'm not liking the macro-economic signals I'm seeing and I like the diversification my wife's Prudential portfolio has (not entirely sold on the fees, but too busy to deal with it right now). I backtested it against every single Lazy Portfolio there is and it's slaying. So me, with my wild-hair annuities and managed mutual fund portfolio - the two most toxic assets you can own, according to the conventional wisdom of every stock pundit you'll meet - am kicking ass over the S&P. That's through a recession and two stock bubbles.
So be careful of conventional wisdom.
Alex over at Ivyvest advises you to shovel 5% of your holdings into play-the-ponies stocks. 5%. So that would be 5% of your portfolio in Netflix, Google, Tesla, Activision Blizzard, etc. He also advises that you don't bother with your play-the-ponies portfolio until you have $100k safe.
Food for thought.
A Beginner's Guide to Investing