well i wouldn't consider myself as a real deal writer, but i am basically a instrumental composer (make up songs with no lyrics, freestyle basically).
Well for me, it will work out if i create the song first, and then make the lyrics. This may sound weird, but it kind of works for me. I make a fast song or slow song and then i add the appropriate lyrics. It will probably work for you too, because since you have the ideal of how the song sounds like (since you have the music created), it will be much easier to create lyrics.
Some people write out lyrics and then create song. Here is what i interpret: Praise songs (most of them, not all) are upbeat, fast-paced songs while worship songs are slow and smooth running. If your lyrics talks about giving praise to God & talk about all the goodness of God, etc, i would put that in the praise songs category. If your lyrics talks about worshiping God & lifting up His name & it talks about Jesus making a sacrifice by dying on the cross, etc, then i would put that in the worship song category.
But this is not always the case; praise songs can be slow, and worship songs can be fast.
The best thing to do is to read your lyrics and examine it. What does it remind you of? What are the emotions? If the lyrics are sad or it makes people want to think or meditate, then you might as well put it as a slow song. If the lyrics are uplifting and joyness, then put it as a fast song.
Now it is quite difficult to make the song not sound like any other song, but it is okay if a little part of the song sounds like one of the famous gospel songs. I would advise you to first try and create a melody of your own and make sure the lyrics connect to the melody. And, in order to add the singing parts: soprano, alto and tenor, just make the chords from the melody. Most of the songs' melodies are sung by sopranos, but in some cases, it is sung by alto.
For example, if the melody is C, E, G, then the chords can be Cmajor, Emajor, Gmajor. Also, you have to know how to invert the chords, just in case you want inversion.
Hope this information helps
