Start from the song, not from the accompaniment. That sounds obvious, but a lot of people never do it.

Decide what the intention of each song is...Decide whether you want to sing it free or in time, fast or slow, loud or soft, decorated or plain...Learn it gradually. Unaccompanied. Take time...

All this time there should not have been a musical instrument in sight, other than perhaps to pick out the melody. Accompaniments are the last thing to think about. If you think an accompaniment will help, put in a simple one. Put it in for a musical or textual reason,not just because you wan to play your guitar.

That quote in italics comes from the introduction to a handy selection of songs called The English Folksinger published about 20 years ago, by the editors Sam Richards and Tish Stubbs. I think it says it well.