I like to have my car fully prepared a whole week before the show,basicly whatever the show date imagine its 7 days before,you wouldnt believe the amount of times this has saved me hartache.
Become an 'expert' on the marque you are showing, as Bob G said,know what is a correct part for your make and Year of car,you can bet any Judge worth his salt will know,and if it comes to a tie,correct finishes might be what it comes down to,the Judge will more than likely be just as enthusistic about your make of car as you are,if you show your've taken the time to get your car as original as possible it will go in your favour,personaly when Judging,orignality (or original type finishes) has a big sway with me, as much as cleanliness.
Be critical on your own car,look at parts which are not upto the same standard as the rest of the car and replace them.Get someone else to look at the car and give you feed back on anything they notice,Mrs.Concours does this for me and although she is in no way a car 'person' she knows what she likes and if something looks 'right' or 'wrong'.
Get the correct era battery (at least one that looks like it) for your car.
Look around at the other competitors cars,take your camera,I ALWAYS ask if I can take photos first,this more often than not leads to a conversation,ask them what the hardest thing to get right was,what the wish they had done differently,what was hard to get hold of,ect,ect.Always nice to ask a name to if there in the same club.
When the Judge comes over I normally just open her up and stay out of their way,speaking from experiance,you basicly just want to narrow the field down to the top cars and not really 'chat' but if someone was clearly a newbie I would take time to answer questions if possible,would have a better talk if I came back for a second look which is usually a good sign if a judge does this!This would be a good to to relate how long/hard it was to get the correct original finish on an unusual part ect,possibly ask them what the drive themselves.
Always found the little folding camping chairs really useful and a picknick is always nice.
Bring your own water,for washing the car,in a large spring water bottle,as you can' always get water on site.Collapsablr buckets save space.
I you can find a garage with a jet wash close to the event make use of it.
Bring family or a good mate along to help you,sometime they will bring a car along with you gear to'support' you.Let then do what they like to do detailing wise.
If the event is miles away,it might be worth traveling up the day before to give yourself enough time,DO make sure the car has security like a steering bar/lockif your going to leave it somewhere unfimilar,might be worth tipping the conciage to keep an eye on it.
Have 'show' mats and everyday mats.treat them with 3M scotchgaurd when new.
I like to use a high(ish) shine on the inside of the tyres (AA,AG rubber and Vynil)and low shine (PB B&B) on the outside.
QD the car at the show DONT use a polish/wax as you are bound to miss somewhere with the time pressure.
Remove all the door/boot (trunk) rubbers and clean behind them,clean rubbers and refit.
I can recommend Mike Antonicks book 'Secrets of Corvette Detailing(second edition) ISBN:0-933534-44-2 publisher Michael Bruce Associates inc, although obviously about Corvettes it gives a good overview on showing cars,some recommended products are a lttlie out of date (thanks Autopia!)but overall it gives a good foundation if you want to get 'into' concours,I think its still in print,you could try ebay PM me if you have trouble locating a copy.
JB; Nice to see you back again-Missed You!
What is concours the scene like in AUS?I was over in Perth WA last December and saw very few Porsches out there,unbeliveably swirly 'normal' cars to. :shocked
