Crediting style 1st to send visitor or last to send

What is best practice or the norm?

[artdog]

Starting up a new affiliate program and need input on the best way to handle this. Having been an affiliate marketer I can see both sides but can't decide.

Which is best or the norm, credit sale to the first affiliate to send visitor or the last to send? First in makes sense because they were there to get'em up front, but, maybe they can't convert and customer moved on to another that does a better job, last in.

Interested in perspectives from advertisers and publishers, really want to do the right thing.

[ccDan]

Bob wants to buy a widget. Joe says, "Hey, go see ArtDog, he has some good stuff." Bob goes to see you, looks around, isn't sure, doesn't buy anything.

Bob talks to Jim about his widget needs. Jim says, "Bob, go see ArtDog, he has some good stuff. I just bought some stuff from him a month ago, everyone loves it. And, he'll treat you right. When I had a problem with my first widget, he took care of me--was reasonable too. If I were you, I'd get your widget from ArtDog."

Bob goes to see you, and this time buys a widget.

Who should get the referral fee, Joe or Jim?

[Marcia]

There's too much room for abuse with first click in, last click is normal and is what's usually done for who gets the commission.

[artdog]

Yea, that's what I lean to, Jim did a better job for conversion and thus deserves the sale and who wants to be gamed anyway.

Thanks