What Alice said.
That, and I'm usually afraid whatever I might make may get locked. Though if it's an RP, for example, I might PM the whole thread to a fellow RPer (and most likely a friend) to see what they think of it, so I can make whatever changes if need be so it'll get accepted right off the bat.
Then, with a Wi-Fi giveaway thread (which I did ONCE), I'll just post it, since I -think- I understand the gist of it (no trading/asking for cheated Pokemon, etc.).
Other than that, I normally don't make threads. Although OVP would be a nice place to start a thread... But Nica usually steals all the fun, random polls by then XD