Congrats on your first-ever submission, man! Your music is really solid; you know how to transition to different sections well, using risers and melodic build-ups. I'd say to try to experiment with different approaches to making a song. I noticed that you liked using a 3/4 waltz for two of the first songs, which is cool if you change how you approach that concept, but it might get repetitive for a submission if you go about it the same way. Playing with tempos and rhythms within that time signature really helps with that. Your mixing wasn't bad at all to me, so all I can do is just give tips I learned in audio engineering class: use buses. if you have a delay or reverb that you want to use for multiple things, use one track for just the reverb and route all your other tracks that you want to have reverb to that track. This helps a lot with making things sound more cohesive and is just an easier workflow compared to putting reverb and delay on each track individually. Also, cross-reference music you like and just try imitating how they pan and mix things. Lastly, use multiband compressors and EQs on your master track. There's one in FL Studio called Maximus that has presets I really like. Try playing around with these tips, and you might find that your music sounds more pleasing to your ears. Keep it up man!