Hey everyone. I've received private messages in my game requesting "Access to Game Name," but I'm not sure how to actually give them access and let them post. Do I have to add them as a player first?

I was hoping for visitors/potential players to be able to post in a character thread on my game's forum before choosing players.

No can do.  You have to add people as players to give them permission to post.  Nothing stops you from removing them later, once you have chosen players.

Hm, okay. Thank you.

I have allowed people to have access to my game by giving them a funny "character" name such as Lookie Lou so that they can interact in the OOC area and enjoy access to all of the threads.

I do the same thing, but I just put "OOC" as the first part of their character name and then the name they want, like "OOC Bob".

That's a good idea.

I've joined a few games where the GM added anyone who submitted a request, but they started out as 'Character 1', 'Character 2', etc until such time as they completed their character generation and had everything approved by the GM (as a matter of fact, that was an additional way of keeping track of who was ready to play...as they got their characters done, they would be renamed, so it was easy to keep track of who was still working on stuff.)