What you want to do is ask yourself how much risk you're willing to take, and how active a role you want to have with your money. For me, I love managing my money, it's something I actually do enjoy, along with picking individual investments. For others, ETF's serve all the purposes you want, and with ETF's(exchange traded funds, a low management cost mutual fund that acts as an index) you can place money on entire sectors.
Another thing you're going to want to do is diversify your investment approaches eventually, there are many different ways of diversification. There's sector diversification(healthcare, industrial, tech, insurance, financial, etc.), there's country diversification, there's investment vehicle(stock, bond, REIT, actual rental properties), there's prime driver of gains(dividends and reinvestment, capital gains[stock appreciation]).
The last thing you're going to want to think on is your investment timeframe. For a small timeframe, stocks can be incredibly dangerous, any bubble can form or collapse at any time. For a long timeframe(5+ years, especially >10) stocks are a great long term investment. For me, I'm totally willing to see my net worth be cut in half, because most of my investments that are self managed are long term companies that I am DRIP'ing into(dividend reinvestment plan, buying more shares with the dividend I gain for owning the current shares), which means that in the event of a major market collapse, if my dividends don't dissapear, then I get to own more of the stock for cheaper, a win-win if you ask me. Again, self managing is a personal choice, and is incredibly unlikely to outperform the market in the long term for almost all investors. The best long term predictor of good returns is well chosen diversification, such as proven by Harry Markowitz when he earned a Nobel prize for his efforts.
So my advice is to think about yourself, and what your goals are and how you are.
