Why don't you start with say four lines that say what you want to say in the song. They can either make one strong statement or four individual statements, or two statements. At this point, don't worry about meter or rhyme.
If one statement, then write corollary statements, one for each main reason for the song.
If four statements, the write four lines on each individual, or if two statements, write eight lines.
Example (and remember that subject is up to you, this is just an example):
I like dogs.
I like all dogs.
I especially like Weiner dogs
I have three Weiner dogs.
Now, you could grab a thesaurus to help you here. That isn't cheating. Or you can look into, say Rhyme.com whatever floats your boat.
I have been around dogs since I was little.
Life without dogs is lonely for me.
I used to think I only liked big dogs,
But now I realize that I really like all shapes and sizes.
But someone got me a miniature dachshund.
And he was so great I fell in love with the breed.
Now I have two more miniature dachshunds,
and if I could, I would have a dachshund farm.
This of the first quatrain as your refrain, and the other two as verses.
REF:
I like dogs. = My heart goes out toward a canine
I like all dogs. = The ugliest mutt to me looks fine
I especially like Weiner dogs = But Doxies are the bestest things
I have three Weiner dogs. = I have a trio, my heart sings!
Verse I:
I have been around dogs since I was little. = Ruffy was my best friend when I was just a tot
Life without dogs is lonely for me. = Always there, on my side, the best friend I'd got.
I used to think I only liked big dogs, = Her big frame held a big heart, and meant a lot
But now I realize that I really like all shapes and sizes. = to me. But all dogs have that gift, I've found.
(okay I couldn't think of an "ot" for that last line.)
But someone got me a miniature dachshund. = My best friend brought me Oberon
And he was so great I fell in love with the breed. = I took one look at him, and I was gone
Now I have two more miniature dachshunds, = And so I got another one, and another one
and if I could, I would have a dachshund farm. = and if I could, I buy the pound.
(Aha! I rhymed "found.")
Okay if I was to go on and one and on, (and believe me I could) I would expound on all the wienery exploits of my friends.
Now this was a top of my head example, and it had not deeper meaning or concern after it, which I am assuming your lyrics would.
But it is a good framework to start with. Know the story or emotion behind the song and once you set down what you want it to say, you can convert it.
I don't do this for poetry, because the form comes very easy to me, but sometimes I am commissioned to write commemorative pieces that MUST contain certain information. Then, I do come back to figuring out what order I want to say things in, do that in prose and then convert the prose to poetic format.
I hope this helps you!