There are three main points when you choose an eyeglass frame for your face shape:
First,it should be concordant with your personal features.
Second, the frame shape should contrast with your face shape.
Third, the size should be in scale with your face size.
Generally speaking, people with triangular face need a semi-fimless frame to accentuate the upper face and a top-heavy style to balance the width of the jaw. Try to avoid choosing low-set temples and narrow frames which will make you look quite strange.