I don't know your handwriting level. Generally speaking, hard-pen calligraphy is not only a competition of calligraphy itself, but also a comprehensive evaluation of practicality and aesthetics. My experience is that it is best to choose long couplets, thousands of words or ancient poems. In short, the fewer repeated words, the better, even repeated words must be changed. Format is also important. Hard pen calligraphy generally has two layouts: horizontal and vertical. I usually use 15 mm vertical grid spacing in the competition, and the effect is better. Horizontal grid generally uses12mm; The choice of font can be based on what you usually practice the most and feel best; Choose a thick and elastic pen that is commonly used, and only absorb half of the ink to write.
Finally, when writing competition works, we must pay attention to the overall layout of rules, the echo between line spacing and the standardization of style. I wish you good results in the competition.