Buy product then review it then promote it. Works?

That makes three of us.

I'm wondering if it might mean "approving people to be affiliates" (i.e. in the case of vendors who have elected to "white-list" their affiliates and accept as affiliates only people they know, and/or others following contact with them, or whatever? I don't think I actually know a ClickBank vendor who does that, though).

Yes ... big (and maybe underdiscussed) issue, here. Good vendors tend to want to support and encourage their affiliates.

I think, to quite a large extent, the appalling, secret truth is that the serious affiliates who are going to bring you 90%/95% of the sales don't really care very much. (I expect large numbers of people to dissent from this view, but I'm sticking to it, anyway). Here's the thing: when it comes to stuff like "ready-made banners" and "ready-made emails" and "ready-made articles" and various other affiliate gimmicks, the best affiliates typically aren't going to use yours anyway. Arrogant and opinionated souls that some of us are, we think we can do better ourselves. Usually. Not quite always.

There are far, far more affiliates who are really interested in "affiliate gimmicks", and many who will even choose the products they promote on the basis of "what goodies are available". I suspect, though, that if you ask very long-established vendors with really large numbers of affiliates, they'll tell you that most of those affiliates actually make very few sales. That's what I've always heard, anyway.

Of course, it is good to support and encourage affiliates, and there are various ways you can try to do that.

Having a nice-looking "affiliate page" (preferably one that isn't linked to from your sales page!) helps. On ClickBank, you need to refer to this in your Marketplace listing and on your Vendor Spotlight page.

You can have an opt-in for affiliates and keep in touch with them (on ClickBank, you can't require affiliates to sign up - unless you go for the "white-listing" option which almost nobody does). And of course it's a huge mistake to require a sign-up just to show potential affiliates what goodies you have available.

Encouraging affiliates to contact you, and always replying to them fairly promptly and in a friendly way helps, too ... but I'm not telling you anything you didn't already know, here, and will stop now.

Yes - that's the catch, isn't it? Well, only you can decide this. My comment, if it's worth anything (and there's no reason it should be: I'm not even a vendor) is that it probably doesn't actually cost you anything to give affiliates who might be professional a free copy?

I have absolutely no idea what your product(s) is/are and am talking theoretically only, here, but if I sent you an email like this asking you for a "review copy" and you didn't want to give me one, I'd buy it through my own affiliate link, anyway. If I were unwilling to do that, if necessary, I wouldn't have been interested enough to ask you in the first place (though obviously I won't say so!). But to be honest, I'd expect you to let me have a free copy (and I do usually get one, when I ask like that).