How to draw eyebrows on so they look fab?

hi been drawing me eyebrows on 4 a few months now somtimes they look really good and others ashow i cnt seem to do them the same each time its doin my head in ive seen eyebrow stencils on ebay but dnt no if they wud be any good someone said they were rubbish.wots the best way to draw them on any tips much appriciated.thanks.