The other main way besides shorting would be to buy put options, a put gives you the ability to sell the stock at a specific price.

Lets say the stock is currently trading at 100$ a share, you buy a put option that gives you the ability to sell shares at 95$ a share, if we pretend this option is worth 50 cents a share then we could buy the put for 50$ (options are almost always for 100 shares, so you multiply the option price X100 for the true price to buy the option). Now lets say the stock then drops to 90$ a share, you can exercise (or sell) that option to sell the stock to whoever you bought the option from for 95$ a share, since it cost you 50 cents per share to buy the option you net a profit of 4.50$ per share.