riptips

Here's some tips that may help if you're new to ripping, but I could summarize it all with, "keep it AQAP!"

MASHUPS
Simple mashups should be kept to a minimum, unless there's a great pun/joke behind it, or they sound really good together. By simple I mean, it's a song synced with another song, and nothing else really going on. Anyone can sync two 4/4 songs together (except djfruitsnacks) [UPDATE: HE ACTUALLY DID IT https://www.youtube.com/watch?v=GuFeaxU4vOw]. It's what you do with it beyond syncing that makes it your own, and makes it high quality.
Examples of going beyond are pitched ops/eyys in a Gangnam Style mashup, steel drums/snaps in a Soulja Boy mashup, using SFX from the game in clever ways, messing with timing/using different time signatures, or editing either song in clever ways.
Chances are if you submit a simple mashup, especially with an overused source (All Star, Bonfire, that two to the one song), it'll be rejected; we really get a lot of them...

MELODYSWAPS
In the same vein, anyone can put the notes of the Flintstones midi into another midi. There's many ways to make even a simple Grand Dad far higher quality than a copy-paste job. It can be summed up as, preserve as much about the original song as possible in your edits, and try to have the final product sound as accurate to console as possible.
Use the same volume and note lengths for the instrument you're using, i.e. if the instrument you're using wasn't designed to be a long note, don't do long notes with it. Change instruments when the original song does. Try to tweak the timing of your notes to flow more like the song you're ripping, and keep notes/pitches from the original to blend it all together into an actual legitimate remix instead of lol flintstones theme haha.
As far as accuracy, that differs from game to game, and what output you're able to get from a ROM. Vibrato is something that's frequently missing, sometimes pitch bending or automation channels as a whole are missing, and N64 games are a real crapshoot. Do your best.
Something I would never accept is this horrific midiswap of Pop Star: https://gilvasunner.bandcamp.com/track/grand-star-2
A prime example of putting all this to use is Pop Star (OST Version): https://www.youtube.com/watch?v=6XOqq4O3qqw
Melodyswaps are what high quality rips are about; I'd much rather hear an Epic Flintstones than a simple mashup, and it's far more likely to be accepted. Trying to learn and get good at melodyswaps is essential if you want to be a high quality ripper!

I made two soundfont ripping tutorials/walkthroughs. These could help in some way:
https://www.youtube.com/watch?v=oaAdoMfOo34
https://www.youtube.com/watch?v=9XVJtDxyUXA

BLUE BALLS
The original intention of GiIva was not just to entertain those in on the joke, but trick those that might run into a rip expecting the real thing. Blue balls rips were a great way of doing that. They may be fairly low effort but they can still be very funny!
However, they are very easy to make, and at this point, we're more about entertaining the fans than tricking those out of the loop, so please don't expect them to be accepted. And I'd like to semi-enforce that a blue balls rip should have SOME change to it at some point. It shouldn't just be a straight loop of one section for 3 minutes. There should be some reward to those that persevere. Often this is something at the ending or somewhere in the middle; or it could be a change in what's being repeated. And please do them sparingly!
Blue Sphere has a hilarious ending, as well as being punny: https://www.youtube.com/watch?v=9ykLCKkEjQw
Bronze District is the king of blue balls: https://www.youtube.com/watch?v=AmJEnhs_x8g
I'm also a huge fan of ascensions/descensions, like the OG Megalovania: https://www.youtube.com/watch?v=b7dt_nzIt8s

ETC.
"High quality rip" has an infinite range of meanings obviously, so submit anything you think would be a good fit! SiIva's strength is never being able to know what's coming when you click on a video, and always trying to use new sources and new jokes. It's good to try new things and not get stuck in a rut. Shitposts are encouraged as well, but the joke is essential for them, especially if the effort is low! "Overly high effort shitposting" was often SiIva in a nutshell; effort goes a long way.

Oh, and I really do recommend saving your projects/source files however you can! It can help a lot for improving the quality of things. If your rip has potential but isn't quite there, you need to be able to tweak it based on feedback.