When you have a small amount of followers you need to promote your contests more b/c if you don't noone will know about it. Try reposting the contest pic and if it's an oc drawing contests make sure each of your characters has their own ref sheet so people really know what to draw; a full body pic with a short description of the character and any extra details you think are helpful like age and personality. And you need to have prizes, people won't enter a contest unless they know the prizes and you need to set a deadline for the contest. And ask people who's style you like, and some of your favorite artists too, they just might enter.