As I myself upload the original lyrics of the artists without permission.
The only notice I have on my site is "For educational purposes only", i.e. you can educate yourself on what the lyrics etc. (might) mean.
I know that the only way to protect your work from not being copied without permission is simply not to post it on the Internet at all.
I don't have anything against people using my translations, even without asking permission; posting them on their blog, translating them to other languages or making karaoke videos, as long as they give credit to me.
Although I'd rather have people not use my translations at all, since they're not that good and I try to improve them every now and then. :)
If you use my translations, put a notice where you got them from – a link to my site.
This should be Internet common sense.
The biggest copying of my translations that I've noticed is the posting of my Onmyo-za lyrics translations to LyricWiki without permission.
I thought for a moment about removing the whole section from my site, but decided not to.
For now, I've added a notice to the Onmyo-za page on my site.