Saypro While Condoms Are The Best Way To Prevent Stis If You Have Sex, They Are Not The Most Effective Type Of Birth Control. If You Have Sex, The Best Way To Prevent Both Stis And Pregnancy Is To Use What Is Called “dual Protection.” Dual Protection Means You Use A Condom To Prevent Stis Each Time You Have Sex, And At The Same Time, You Use A More Effective Form Of Birth Control, Such As An Iud, Implant, Or Shot.