Sleepy Rosie, if you want to try lowering your range a little, have a go at a blues or two - try 'Walking to Chicago' and have fun belting it out, but not in a head voice - get the feel of a gutsy, raunchy blues Mama.
Then try something in between - maybe copy Judy Collins or PP&M or even Judy Durham from the Seekers, if you can find recordings of them. Or in the UK, try recordings of the Watersons and Eliza Carthy for a strong natural voice - a diaphram voice.
As SPB and Leadfingers said, most of my songs were 'copied' from recordings of others and, at first, were sung in a voice as close to the original as I could get. (I never did sound like Judy Collins - more like Shirley Collins but I had fun trying all the styles).
Robyn