What's the proper way to make a key truested?

[Bart Martens]

> > I just imported a friend's GPG key -- the first one I've imported in
> > a while -- and I cannot make it trusted. I ran gpg --edit 56791C97
> > tried 'trust' '4' (full trust) save (to which is said nothign needed
> > to be saved) and closed.
> 
> I'm new to GPG, but as to my understanding you have to sign the Key to
> trust it. The "trust" you have edited is how much you trust the key
> (that is, the owner of the key) to introduce other keys to you.

Sign the key when you know the identity of the key owner. Set the trust
value corresponding to the level of your trust in the key's owner
key signing behavior. Signing a key and setting the trust value on a
key are two completely different things.