Hmmm... OK, I think all of these tracks have two major issues. One is the lack of good rhythm. The beats in the DPCM channel of Track 7 works, but is completely ruined by the G note (that drum kick). Try moving it somewhere, where it feels right, or remove it altogether. Track 9 has some good beats, but they get misplaced at some point and it feels uncomfortable. Also, try to place to notes in places where they align better with the rhythm. Track 11 does that, although you still have some notes that are out of place.
The second issue is that the notes themselves feel a bit random. In order to make the song harmonious, you have to pick a music scale for your song, which will limit which notes you can use, but it will make the song consistent (even then you have to experiment and see which notes work together). The arpeggio you've used for Track 11, doesn't really work because of the distance between the notes it uses remains the same. When you use chords, a lot of times, the distance between the notes changes, depending on what your main note is, in order for the chord to sound right.
Now, all this might seem hard, but don't be discouraged. I can guess you're new to making music, so it's only normal to make such mistakes. Here's a few things I recommend that you do: Listen to a lot of music and even try to make covers of NES music. (Make sure you get MIDI file or something, so you can look at the notes) That way, you'll get a feel of how rhythm works and how notes can relate to each other. Read about music theory, to learn more about rhythm, how notes relate to each other, music scales, chords, etc.
This site is a good start (it deals more with sheet music and not trackers, but the concepts remain the same). Remember to experiment when making music. Try out different notes and rhythms, until the song truly sounds right. You'll learn what works and what doesn't that way.
So, yeah, that's about it. Just keep going, learn as much as you can and experiment as much as possible. I'd like to see you improve and make some great music.
