תרגום - אנגלית-לטינית - You only live once, but if you live it right once...

Hi Alex!
One suggestion:
una sufficit --> una satis est

Do you agree?

Ok, I guess it is a matter of interpretation. We can leave your "sufficit" I believe.

how about: "Vos tantum ago quondam , sive vos ago is vox quondam est satis"

I'm sorry, mariannekoi, but your proposition is quite out of Latin grammar.
For example you typed "Vos tantum ago quondam" where the subject "vos"=you is in the 2nd person plural, meanwhile your verb "ago" (I drive, I lead, I do...) is put in the 1st person singular!?
Not acceptable, sorry.

Ok what difference (una sufficit --> una satis est)there is?

No big difference, but it is indeed.

Sufficit = is enough, is adequate, it suffices (so we don't need more)

satis est = is enough, is sufficient (but could be more)

Hope I was clear enough. Greetings!