Photo contests are a great place to showcase you work; however, not all contests are created equal.  I encourage all photographers at all levels of expertise to enter, but my advise is do your homework. 

Several contests sole purpose, it appears, is to make money through high fees.  Research their reputations to see if there are complaints i.e. using the names of judges who were never contacted.  Visit sites like the  World Photography Organization, “whose purpose is to raise the level of conversation around photography worldwide, through a year-round programme of exhibitions, awards and competitions.”

The internet is a great place which will assist you in finding great contests like the Sony World Photography Awards, Nikon’s Small World Competition, or the International Photo Awards (IPA).

Good Luck!