Doing a Little Homework

Experience is a hard teacher. It gives the test before the lesson. Do try and learn from others' bad decisions, saves you from having to learn from your own.
Before you dig in too much deeper, go way back to earlier posts on diversification and rebalancing.
Rebalancing is the only sane way to handle a portfolio. A quickie summary is, if you have your four asset classes divided equally, 25% of your investable funds would be in each. Then, each year, you see how you did. If stocks were UP 20%, bonds flat, cash would earn a bit in money market and real estate was down, then you would sell some of the stocks, and reinvest that capital in real estate, so that your get back to 25% in each asset class.
You are buying LOW, and selling HIGH, which is the idea. People talk about it, but they almost never DO it. The reason generally boils down to, "But I'm selling off some of the GOOD one and buying more of the BAD one."
Those people believe trees grow to the sky. And letting one asset class run way ahead of the others is a sure way to minimize your profit over time.
Diversification is up next. We know we have, for most people, four asset classes. Stocks, bonds, cash, real estate.
But what stocks, what bonds, what real estate? Cash is money market, there's not much to think about, a short CD, T-Bill or money market all accomplish the same thing, safe principal, a few bucks in interest or dividends.
Next up, your choices for the other three.