Sonnets are fourteen lines, as is sonnet 130; this allows Shakespeare to list several qualities of his mistress, then conclude with a couplet that turns the rest of the sonnet on its head. Sonnets have ten syllables per line, as does sonnet 130; this makes the poem read cleanly, with each thought given the same amount of weight in the poem. There are no structural oddities, like shorter or longer sentences, just the steady flow of beautiful poetry. Sonnets are written in iambic pentameter; this makes the singsongy feel of the poem as it compares each attribute of the woman with a quality found in nature
Commas are used when listing 3 or more things and when adding details to something (like saying "Jennie, my little sister" or "Tom and Brent, my best friends").
