Never, EVER submit you photographs to a so-called “photo contest” or “competition!” You will surely be able to read fine print that gives the sponsors pretty much all rights to use your photograph(s), whether you “win” or not, any way they see fit. That includes commercial use. In other words, it will mean relinnquishing your copyright for bupkis to strangers.
Show me one person who has ever successfully jumpstarted or otherwise helped one’s career economically by winning a photo contest, and I will eat these words.
Grant applications to well known and respected non-profits is another story.