Diversify all over the globe.

Every stock price is a guess about the future earnings of that company, and individual guesses can be very, very wrong (just ask former employees of Enron).  Nobody knows the best place to invest, and the consequences of putting too much in one place can be devastating, so it might make the most sense to put your money EVERYWHERE.

Even with only $100 a month to invest, you could open two mutual fund accounts at beginner-friendly T. Rowe Price (a fine organization founded in 1940 with whom I have absolutely no affiliation except as an investor).  If you put $50 each into:

you would have investments in over 3,000 different companies spread around the globe.  So don't tell me you don't have enough money to diversify.

Of course, this is only an example: I've never even met you, so how on earth could I know whether mutual funds are even  appropriate for you, let alone which ones to use?  A sound investment strategy requires knowledge of your financial profile, investment objectives, goals, age, and other factors. 

On top of that, every investment has a risk of loss (stocks can go down and stay down for quite a while, and cash and bonds can and usually do lose ground to inflation over time).  There are many good reasons to consult with an adviser to help you develop a sound approach, not the least of which is that you probably can't be trusted to make sound decisions if you invest by copying down the names of mutual funds from a web site written by a total stranger!