Google "what eyeglass frames are right for me" and you will see hundreds if not thousands of links and videos offering "do's and don'ts" fashion advice regarding what shape and color eyeglasses you should wear.
For example, here's some standard frame selection guidance regarding face shape:
Oval – Your face is taller than wide, with a slightly rounded jawline. Most any style frame will complement your face, though round and rectangular are preferred.
Round – Your face is approximately as wide as it is tall. Contrasting rectangular frame shapes are typically recommended.
Heart – Your forehead is wider than your jawline, which tends to be somewhat pointed in shape. Choose wide frames with thin temples to accentuate your cheekbones.
Square – You have a wider, angled jawline. Round and oval shape work best.
And as for color:
If you are a "warm" palette (yellow, peach or cream undertones, brown or hazel eyes, gold/blond, dark brown, black or red hair), look for peach, gold, copper, brown, caramel, red or light tortoise shell frames.
If you are a "cool" palette (pink and blue undertones or olive skin, blue or green eyes, ash, light brown, grey or slat & pepper hair), select black, silver, blue, grey, green, plum or dark tortoise shell.
All that said, if you've a heart-shaped warm palette face but you like small silver oval frames, don't limit yourself by following other people's fashion rules. Focusers frames are about standing out and being noticed, not about fitting in. Your eye wear is an expression of you. Though it's nice to know what "the rules" are, if too many people follow "the rules" then we'll end up with a society where everyone looks the same. At the end of the day if you want to make a unique statement -- or perhaps even set a new trend -- then it's Your face. Your rules!
And also while you're at it, go ahead and wear white after Labor Day and socks that don't match your pants.