villanelle:
The villanelle is a rhymed poem composed of nineteen lines. The nineteen lines which make-up the villanelle are broken down into five three-line stanzas and one four-line stanza.

Two of the lines, the first and third, of the first stanza are repeated throughout as the third line of the next four stanzas, and the last two lines of the ending four-line stanza.

Using A(1) and A(2) to represent the repeating lines, the basic skeleton of your poem will look like this:

A(1)
b
A(2)

a
b
A(1)

a
b
A(2)

a
b
A(1)

a
b
A(2)

a
b
A(1)
A(2)

Some helpful hints:
1: Since your 1st and 3rd lines repeat throughout, and then must come together as the last two lines, compose them first.
2: Make sure that your end words will be able to make use of many rhymes (including near-rhymes).