You can write any topics which has some relation with Kerala. The most traffic capturing topics are : latest cinema, autobiography of famous personality (which include actors, actress, politicians, sports players, etc.). Otherwise you can write about interesting tourism sites or food recipes of Kerala. If you have some other informations related to your nearby places that rarely others know can be very useful topic. Rare topics will definitely come on top in search engine as such informations are very rare and other sites would not have added it. Best wishes.