(http://omshivam.files.wordpress.com/2010/04/shri-shani-dev.jpg)
One of the best mantras for pleasing Shani Bhagvan is from the famous NAVAGRAHA Stotram composed by Bhagvan Shri Veda Vyasa.
NILANJANA SAMABHASAM RAVI PUTRAM YAMAGRAJAM | CHAYA MARTHANDA SAMBHUTAM TAM NAMAMI SHANAISCHARAM ||
नीलांजन समाभासम रवि पुत्रम यमाग्रजं ।
छाया मार्तान्ड समभुतम तं नमामि शनिश्चरम ॥