Do a lot of reading before putting your money at risk. Personal favs of mine are The Wealthy Barber and it's sequel The Wealthy Barber Returns, and Rich Dad Poor Dad. Those books generally follow the mantra of picking investments (stocks, bonds, funds, etc) that return cash to you in the form of dividends, interest, etc. There are other investments like physical real estate or building a business that can return cash to you, but they are obviously more difficult and risky to get into.
Markets will go up and down, but good investments always generate cash flow regardless. Then again any cash flow investment like stock can stop returning cash to you e.g. dividend cut, tenant leaves, business failure, etc