some horses will be more quick to trust then others, it took autumn a months to trust my instructer or me.
lots of patience, lots of time standing outside the stall or pasture just watching and talking to the horse. i had had autumn for about 2yrs and i walked out to see him one day (i thought there were NO trust issue's between us) and i had a black hat on..he FLIPPED OUT. i had to take the hat off and even then it took him a while, but he soon came to me. i assume it was the hat.
just lots of patience and love!