The best type of competitions to advertise with this gig are email submit or Facebook like and share, cash prizes or vouchers are most popular. If people have to write 2000 words on why they like cats you won't get many entrants!!!! If the prize is a pencil you won't get many entrants!!!!
Prizes don't need to be really valuable but if they are not desirable people won't want them!
No affiliate links please.