Rhymes have the best success when they accentuate the meaning, theme, or purpose of a poem.
Since the repetition of a sound naturally calls attention to it, this can be a useful technique to highlight an important thought or image. Otherwise, the emphasis of rhyme can be distracting – like pointing to an empty doorway and saying, "Ta DA!" when nothing is there.
If you once thought, as I did, that a poem wasn't a poem unless it rhymed, you may have found yourself being faithful to the rhyming pattern rather than the poem’s meaning. However, rhyme for the sake of rhyme can make a line seem odd, awkward or strained, so it's better to omit rhymes altogether than to force the syntax into an unnatural-sounding sentence.
In general, the weakest rhymes use the weakest words to create the weakest pictures. For example, a preposition, adjective, or adverb can not be envisioned. Except for providing a senseless sound, nothing is gained by pairing a rhyme with “of,” “for,” “the,” or other abstract word.
Conversely, the opposite is true: Strong nouns and verbs offer the strongest rhymes, create the clearest pictures, and give the greatest strength and emphasis to a poem’s meaning, theme, and purpose as I hope this poem will show:
The cardinals convene the color of the day.
Robed in red, they pronounce a benediction
over cawing crow and squawking jay –
an ecumenical procession of beak and plume.
Two tiny titmice, cowled like monks,
begin to chant, and a pair of mourning doves
peck flat wafer seeds from green chunks
of ground, keeping time to some hymnal tune.
A brown thrasher thrashes in a purifying pool,
and into this God-given school of earth and sky –
on my most mid weak day – I
come to be quiet and commune.
Note: The above post primarily came from the ChristianPoet’s Guide to Writing Poetry e-book.