Best way to do 301?

Hello,

I am looking to do a 301 Redirect on one of my websites from other domain, my question is do I do redirect on a post or category? Doesn't juice get lost on category? Because if I do on post I can place link to home so, juice goes to home.

Also what is best way of doing it on htaccess or in domain registrar?

What you guys think?

Thanks