The first, Entering Costume Contests at Comics Conventions, has tips for the more ambitious cosplayer, looking to win big at the con masquerade.
The second is Comfortable Costume Ideas for Comics Conventions, aimed at the more casual convention-goer.
The good news is that a lot of this great advice (if I say so myself) also applies to Halloween costumes – start planning now, folks! The bad news is that there's more alliteration in those article titles than I would normally like. Oh well.