Others have commented on the value of investing in index funds, target date funds, ETF's etc. All that is well and good, and is advice to be followed to a point. If you have some money to literally "play" with, however, than investing in individual companies is fine too. Just don't put all your eggs in one basket and invest in companies you understand.
Here is a good article about how warren buffet analyzes potential investments.
http://www.investopedia.com/ask/answers/081114/how-does-warren-buffett-choose-what-companies-buy.asp
It is a lot of common sense, and basically comes down to - understand the target 's financials and how they make money, determine how much of a discount the shares are being offered at (the tough part), and if all looks good, invest.
Historically, Buffett has focused on companies that provide goods that are unique, highly profitable, and consumer staples. E.g., Coca Cola, 3M, J&J, P&G, etc. Its hard to buy those companies at a discount now because lots of people understand their value. In the tech world, though, there are probably quite a few companies that provide unique products for internet/business infrastructure, but which are less well known and therefore more likely to be available at a discount.