Rhyming :
Do not stress a poem with rhymes, it doesn't really help if you have to stress the poem to it's utmost.
No one really wants to read a poem with rhymes that are put there just for the sake of a rhyming scheme. If your second, or third, line no longer follow the poem's subject and flow because of it's ending in a rhyme, then change your scheme or rewrite the poem.
I have too often seen someone sacrifice their poem for the sake of a rhyme. It does no one any good. It just ends up sounding, and reading, horribly.
