What these guys said - if you are serious about wanting to do a show & not being a cheeseball up on the stage, you need to know what poses are going to be required, how to execute them at the morning judging and also how to present the best stuff you have during the posing routine, and let's face it - you want that FINAL POSE DOWN to be YOUR SHOW right?
But seriously, you the above mentioned videos will give you the basics, but you should definitely find someone who can help you. You can ask around at your gym, but I wouldn't go with just a trainer who has never done a show or trained others for a show. If they've never done the whole routine (show), then you are going to feel really stupid when you realize there was more to it than just going up on stage & flexing. It's not rocket science, however there is a "way" to prepare for & do a show. Ask around your gym & see if there are other people who have done a show or who can recommend someone who helped them.
Another thing about posing is that as you are coming up to your target show (e.g. 2-3 months out) you want to start adding posing sessions to your training so not only can you learn how to hold a pose for 30 seconds (or longer if you get really evil judges at your target show) but also it will do amazing things to do that final leaning out & tightening prior to the show.
If you have a target show in mind, find out what organization is sponsering it (e.g. NPC) and make sure that its NOT a tested show (not tested for steroid use). Also see if you can talk to anyone sponsering the show about what posing requirements there are as some organizations or even shows have different requirements.
Its also nice to see if there is at least 1 other show around the same time as your target one so you can take advantage of all your prep time - you will be able to hit more than one shows while you are all hot & ripped looking. Also if you end up having a conflict w/ the date of one of them, you have a fall back so you don't have to just toss the whole experience. And finally, if you hit the first one, talk to the judges & get input on what you can do to improve and also take the extra week or two or three between shows to tighten up your bodyfat or any other things you could've done better in the first show. And then, since you will have already done one show, you can relax a little bit at the next one & be an old pro
