Do I simply post a thread and offer the codes to the first 5 persons who reply or should I ask for PMs? What would be the proper procedure?
You can give away codes however you'd like. Some developers simply posts lists of codes, others ask people to PM them. I think that the best way to give them away is through some kind of contest or guessing game, but that's just me. Ideally you want to generate interest in your game, so if you've got a bunch of people bumping your thread posting images for a photoshop contest or something you're going to stay on the top of the forum listing for a lot longer than you would if you just posted a list of five codes. But, like I said, they're your codes. As long as you're the developer you can give them away however you want.
You can do that however you'd like, they are your codes However, if you just post them freely, you are at higher risk that you won't get reviews in itunes for them and lurker take them very quickly an dyou may not get any feedback. Contests are always the best way (I think) to give out promo codes, or making them try out a lite version of the game (if you have one). PM's is perfectly fine too though. And yeah you can just make a thread announcing your promo code giveaway/contest or whatever. EDIT: wow hodapp, you said the exact same thing I did, just seconds earlier.
There is no proper procedure but you should give them out in the thread about your game. If you ask for people to reply then you can PM the code to them. Depends if you want alot of PMs.
I like PM's or contests, becuase PM's you don't have to try each code to see if any are left and contest require you to do something for the code