Hello Matt.
The events I attend you need to call out your maneuvers and announce Beginning and Ending at the start and end of the maneuver. Generally I do all of mine up wind a little bit outside the runways edge. Depending on the maneuver and daytime conditions before the flight I might place it in a different spot.

For instance if the sun is going to be in a bad spot during a immelemen I will tell the judges before the flight I am going to offset this maneuver to the right to avoid the sun. This also helps you because Its allot harder to see the exact starting point and ending point so it can be esier to get a better score but it also makes it easier for the judges to see heading changes. So say you have a strong crosswind then this might hurt you offsetting it if you dont put enough rudder into it.

On something simple like a roll on a normal day can be challenging during scale competition. First you want to bring the nose up slightly then do slow airleron roll with the aircraft being perfectly inverted right in front of you. You need to finish at the exact same altitude you started at and the roll needs to be the same exact speed the entire time. On one day you got the timing down then the next day you have a strong headwind and now you end up rolling to early. So be aware of the winds because they will change everything you do.

For my inverted pass I start from inverted meaning before I get to the runway my aircraft is already upside down and aligned perfect a little out side the runways edge. I tell the judge begin when about 300 feet from show center and count out loud in seconds (1-2-3) until I hit show center then begin the count again (3-2-1) and call maneuver complete. After I call complete and fly in a straight line for a few seconds I then flip the aircraft back over. This keeps the distance of the manuver the same on both sides. You also do this on other passes that are straight like a dirty pass or high speed pass.

Even something like a simple military break can get complicated. You need to begin this maneuver right in front of you and do a perfect arch when the aircraft is at 180 degrees it needs to again be aligned with you when you level the wings. Now for my plane I enter the maneuver pretty slow but advance the throttle to full power right before breaking. This gives the illusion that I am not flying to fast and also lets me get the afterburner lights turned on when the airplane breaks away from the judges. After I am halfway through the turn I reduce throttle to about half throttle so the aircraft slows down some. This helps in keeping the aircraft turning at the same rate of speed. If I kept speeding up it would be tough and I would need to pull more and more elevator and the aircraft would exit at to high of speed. But this is all related to my aircraft and my or may not apply to your aircraft.

For maneuvers where I climb pretty high or if im going to end up flying against the flight line traffic I do these about 40 feet from the runways edge for two reasons. One the judges sometimes have some type of sunshade over their head and if you do these right next to the runway they cant see it. This will effect your score. You always want to make it easy on the judges. Number 2 is when your doing say a half cuban 8 you have less of a chance hitting opposing traffic in the middle of the flying area.