This thread is meant to be a discussion/reference/repository for musical techniques and compositional strategies that are useful for creating "interesting" and "entertaining" results. I know these are all subjective terms and techniques; it's for creativity's sake, and will inevitably help those who seem to be "stuck" on their musical evolutionary path.
I think what songwriters--new and old--need is a handful of techniques that they can look over and bounce ideas off of fellow chipmusicians after creating what they believe to be a finished product. This not only helps you grow as a musician, but also shies you away from hastily releasing that potentially uninteresting EP or LP, as most of us have experienced. These are not meant to create uniform structures (like pop music uses), but to enhance creative & free expression by introducing musical and thematic elements that may not have crossed a musician's mind.
I'll start things off by sharing some techniques I've been jotting down as I compose pieces for a future release... note: the theory in my explanation is basic, so shouldn't be hard for folks to understand. I'll use C major for all examples:
Instrument Contrast: Vary instrument sounds throughout the piece. What could've worked well in the intros/verses may not be suitable for the choruses/bridges. Using different tones and timbres throughout your piece can entice listeners to stay and listen. Use more than... hey I have this sweet ass guitar/synth tone here in the verse, lemme reuse it for the chorus. Nah b, change that shit up to be like 10 times better for your climax!
Melodic Variation: Melodies should have highs and lows... try not to repeat the climax of a melody over and over, it ruins its "catharsis." Also, the chorus melody SHOULD be the most climactic part of a piece, above all else using the tonic note (note of the song's key) more often. Mountains (ups and downs) are usually more interesting than barren flat-lands (Single-note melodies).
Chordal Accompaniment: Too many irregular chords side by side can create a very disjunct sound. I usually put the bass notes in, taking care not to have any awkward/huge leaps, then fill in the rest of the chord voicings after. This creates good voice leading (something that can really cause a song to sound either awkward or smooooth as butter). Also, stronger/clearer chords should be present in the chorus... the "weaker" sounding chords usually exist in the verses/bridges.
Key Change: Key changes can shift the listener's ears and thoughts to a different mood within the context of your piece. Usually, the bridge of a song introduces a slight modulation (say, from major to its relative minor), and works with a newly formed melody to create variation. Key changes can even occur in full by altering the entire key (say, playing the chorus in the original key for a short duration, then modulate to another key for the remainder.)
Lead Harmony: If done properly, melody harmony can add huge variation to a repeating melody. Some techniques include leaving out the harmonies for the first pass of the verse, then adding them in during the second pass; letting the chorus play once without harmonies, then add them in upon repeating; using harmony sparingly across the piece, really bringing out specific parts of the song.
Phrasing: Chord progression and melodies can interest the listener if they aren't fully resolved to the original chord (tonic) the first time around... kind of like a question/answer. If I asked someone, "hey, how did you manage to get Usher's big toe?" you'd probably want to know the answer. If you start a melody on C in C major, don't bring it back to C the first time around... maybe end it on A (the 6th, which is minor in a major key), accompanying it with a A minor chord. THEN repeat the melody with some variation, and bring it back to C at the end, accompanying it with a tonic C major chord.
Resolutions and Cadences: Chords that don't contain any notes of the tonic triad (a C chord of a song in C major) should in some form be resolved by the chorus or last chord of the song. Dominant chords that don't resolve to the original chord of the key (tonic chord) can also create dissonance or instability in a song... maybe the bridge (which is sometimes a great thing). End the first phrase (as I've mentioned previously) by using a 5 chord (G in C major), then a 6 chord (Aminor in C major) like mentioned above. This is a deceptive cadence. End the second phrase using a 5 chord, maybe adding in a 7th;) (G with an F in the chord), then go to a tonic chord (C major in C major). This is a perfect cadence (as long as the tonic note [C] is in the bass).
Innovation and "Newness": Why is your song special? Think of what you can do to make this a fact. Sure you've used arps... they're great but they seem to be very popular and overused? They were innovative in the 80s when programmers couldn't use multiple channels to articulate all chord voices. How can you innovate this? Or, sure I've got a four on the floor rhythm that's kicking ass, but we've heard that before... maybe I can throw people off by adding a jazzy swing; introduce a little chaos then return to your main idea and it will become that much more interesting!
Spatial Atmosphere: I think this is evermore important to chipmusic as it is to any other mediums/genres (other than maybe to soundscape compositions themselves 
). Assigning accompaniment to either left or right in the listener's ear can let us manipulate where we'd like the listener to pay their attention. If you've got your melody deceptively going from G to A at the end of the first phrase in C major, you want your listener to take note of this so they can tell the difference the next time around once you bring it back to C (tonic in C major). You can pan the chordal accompaniment left and right so the bass/drums/lead melody can remain clear in the center. This also applies if you want a fat bass/kick to stand out. pan other things left and right and BOOM. listener will get the full frontal force of the stuff without having it muddied up by the chords or lead.
Dynamics: Okay... so if we want the chorus to be the catchiest/most climactic part... shouldn't it be the loudest? Not always the case, but the main principle is there. Adjust your volume levels based on which point of the song its at. The introduction can be fairly quite so when the first verse comes in people will become more interested/engaged. Once they pass the verse, the next part of the song can be a bit louder with some awesome buildup, put in your little dropski mcgee then BOOM pump the volume of the chorus up a bit to contrast with what the audience thought was the max volume of the tune. Be careful, though... don't make the instruments TOO quiet.
The Introduction: This is where you'll either draw your listeners in or push them away. Most people will listen to it and think either "n00b," "it's alright/getting there," or "old timer/hell this is good." Make the introduction interesting by combining all the ideas mentioned here. This doesn't mean make it crazy busy.
Follow Your Instincts: If you think a melody/progression should go to a certain place... put it there... don't let these guidelines hold you back. Music is expressing emotion in the first place, so put your emotion into it by letting it happen. These techniques are here for you to look over and think up any extra possibilities according to your instincts.
this website is a great resource, as well.... though I don't really think there are "secrets" to song writing.
Anyways... hope y'all like this idea. ChipMUSIC seems to need more musical discussion. Also, I don't think this is a tutorial necessarily... there shouldn't be a tutorial for writing music.
Please elaborate on some of my ideas as well! Keep in mind all of this stuff is a learning process... For instance, I haven't added anything about mixing/mastering because I'm not entirely there yet in my process.
I just think it'd be a good idea to have some sort of compendium of how to vary your songs to sound pleasing before making the mistake of prematurely releasing tunes that maybe don't satisfy you. If anything, hopefully I/we can use this topic as a public database for creative songwriting.
I can edit in your ideas to the above list as things go if that'll serve the purpose of the topic better.