Chanting Mantras reduces much evil. These mantras must be chanted during Sani hora or sani rise time facing west
Mantra for Shani :
Beej Mantra : Aum Shum Shanaischaraaya namaha
Tantric Mantra : Aum praang preeng proung sah Shanaye namah
Sani Stotra : Neelaanjana samaabhaasam raviputram yamaagrajam, Chaayaa-maartandam-sambhootam, Tam namaami Shanaishcharam
Shani Gayathri : Kaaka Dhwajaaya Vidhmahe' - Kadga Hasthaaya Dheemahi Thanno Mandha Pracho Dhayaath
For all Saturn related troubles the following Shani Shodasanama stotra of Dasharatha is an excellent remedy
Konassanaischaromandah chhayaahridayanandanah
Maargandaja sudhaasouri neelavastraanjanadyutih
Abrahmanah kroora kroora karmaatangi grahanaayakah
Krishnodharmaanujah shantah shushkodara varapradah
Apart from this reciting the following dasanama stotra of Shani by Dasharatha near a Peepal tree is also a highly recommended one.
Konastha pingalobabhruh
Krishnoroudraantakoyamah
Souri, shanaischaro mandah
Pippaladishu sansthitah