3. Eating the right things at the right time
At most Crossfit competitions you will do 3-4 workouts a day. If you are attending a multi day event, it may add up to 8 workouts in two days, which is extremely demanding for your body and its functions. In most cases the only normal meal will be the breakfast. Focus on that! This could safe your life during those days competing.
Source: RX'd Photography
Try to consume up to 1000 calories (I am not kidding) at breakfast. It will build enough foundation to offset at least the first workout. Eat breakfast 2-3 hours before the first workout. Later, eat and drink after each! workout, even if the WOD was one max rep lift only. There are thousands of Crossfit competition articles on what should be included in those meals. In reality athletes will even find it hard to eat anything. Therefore just eat something. Please no garlic soup, which was made by your aunt.
I tell my athletes to make an eating plan beforehand and stick to it.