Now I am studying class12.In my 1st year I got 280 marks average in weekly jeemains mocktests conducted by our college.Advanced average is not better.I am feeling bit tensed.Can u plz suggest how could I utilise this one year to crack jee advanced?

look you are good already if you are scoring that much marks in jee main exam mock
so now you have to concentrate on difficult problems mainly..i suggest you please do solve iit-jee last 35 year question you will get an idea about questions and also join a test-series