If you are a woman composer and are looking for some competitions that are not restricted especially to younger composers, then take a look at what the International Alliance for Women in Music has to offer:
The IAWM holds an annual composition competition for women composers called the “Search for New Music.” This international competition includes ten different prize categories ranging from chamber and orchestral works to electro-acoustic media, improvisation, and sound installation. Each prize has its own monetary award. Membership in IAWM is required to enter, but contestants may join at the time of entry. The SNM committee administers the competition, receives entries, selects judges and publicizes the contest guidelines and the list of winners.
Included in these competitions are the Judith Lang Zaimont prize and the Ellen Taaffe Zwilich prize. My composition and I studied Zwilich a great deal in my program, so I’m always more interested when her name is mentioned.