Start in basic, flying for a score and in front of everyone watching is way different than just doing it. There is no shame in starting basic and you will learn a lot. Remember, the best score wins, so ask yourself the following and answer yourself truthfully:

Are you able to hold a perfectly straight and level line for several hundred feet and can you do a full roll on that line without losing any altitude and causing a heading change, do you know how to make sure you 45 degree lines are actually 45 degrees, are your downlines perfectly straight down. Can you do a perfectly round loop that starts and stops at the same place, Can you do a perfectly round 360 degree aerobatic turn that is exactly 360 degrees and not lose or gain altitude and have the same roll rate coming out as you did going in. Do you know how to center an element on a line.

Are all of the above being done wind corrected?

It's a lot harder than it looks but at the same time it's tons of fun and certainly teaches you how to handle a plane and place it where you want at anytime you want.

Another thing is most likely you will be flying against the same people all the time and being judged by the same judges most of the time. Though a CD tries to pass around judging duties, he sometimes has to rely on the same ones. Most likely you will be judged by the guys flying advanced or higher and they have been there and done that and know exactly what you are going to do before YOU know it, IE they have a good idea where you are going to try to hide your rudder corrections, where you are most likely to come out with the wings unlevel, etc... and can tell quickly that you are 5 degrees off before you see it.

I am sorry if the whole post sounds negative, it really is not meant that way, what I stated is what you need to know plus there are a few things I did not touch on.

Try this on for size. It will tell you just how good your rudder skills are which are needed in all IMAC. You must maintain a level line and you cannot deviate the roll rate or heading, the hesitations between the points must be the same and when you complete the hammer the first 3 or 4 must be opposite of the first one you did before the hammer and the 1/2 rolls must be centered on wherever you are standing.

3 of 4 to the right
1/2 roll to the left
3 of 4 to the right

Hammer (nothing up or down)

3 of 4 to the left
1/2 roll to the right
3 of 4 to the left