After the handshake, it is easier to talk to each other than otherwise.

After the handshake, it is easier to talk to each other than in a situation where we don't shake hands.

It is easier to talk to each other in a situation where we've done handshake than in a situation where we haven't.

There's something amiss with each of these sentences.

In the first, it's not perfectly clear what "than otherwise" means, because you begin the sentence with "After". Otherwise could be "before the handshake". Otherwise could mean "if there is no handshake".

In the second, the items on either side of "easier" are not true comparands: after the handshake and in a situation where.

In the third, the comparands are correct (if somewhat wooden) but "done handshake" is not idiomatic.

It's easier to talk business after shaking hands.

After the handshake, it is easier to talk to each other than otherwise.

After the handshake, it is easier to talk to each other than in a situation where we don't shake hands.

It is easier to talk to each other in a situation where we've done handshake than in a situation where we haven't.

There's something amiss with each of these sentences.

In the first, it's not perfectly clear what "than otherwise" means, because you begin the sentence with "After". Otherwise could be "before the handshake". Otherwise could mean "if there is no handshake".

In the second, the items on either side of "easier" are not true comparands: after the handshake and in a situation where.

In the third, the comparands are correct (if somewhat wooden) but "done handshake" is not idiomatic.

It's easier to talk business after shaking hands. (or after a handshake)

P.S. If this sentence were in a discussion of the role of the handshake in Western culture, then you could say after the handshake.