I wish there was a proper tutorial. The only one I keep finding is for Sega Genesis rips, and is
very outdated. I'll give you a rough tutorial.
Step One: Obtain a VGM logging-capable emulator/player.
viewtopic.php?t=107
I recommend using M1 if you can, you'll be fine as long as you know how to use DOS-ish command lines. I don't recommend MAME for beginners, as it requires splitting a giant VGM file into smaller chunks afterward. But sadly it seems to be the only way to get Skull & Crossbones
Step Two: Trimming & Optimizing
For this step you'll need VGM Tools. It has a readme explaining what each program does.
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Generally, here's what you'd do. Use vgmlpfnd to find the loop point in each track you logged in M1, then use vgm_trim with the loop points you found to trim the file and make it loop properly. (To get a good estimate of where loops are, some record them as WAVs then load into Audacity. I just do it by ear and Winamp's timer). Afterwards you'd run vgm_sro to optimize any samples, followed by vgm_cmp to compress the VGM further.
Step Three: Tagging
Once you have all the nice, optimized VGM files. You should tag them with Composer, Track Title, Game Title, etc. This can be done in
VGM Toolbox. There are
standards to this. Namely...
1. No using composer "nicknames",
VGMdb has a listing of them. So if you come across any, just be sure to use their actual name when it comes to tagging. Most of the time it also has their proper Japanese symbols, which is good if you're also doing Japanese tags.
2. Track Titles. OST Listing>Game Stage Title>Generic Level #
Again, if it has an OST. It's usually recommended to go by that. I know M1 will tag a bunch of these fields for you, but it's a very good idea to double check on your own.
3. Game Release Date. The more precise the better, but just do the best you can.
Once you have that, there's a few more topics to tend to such as filenames, and how to make a pack suitable to upload to the site. Which is already covered by this ->
viewtopic.php?t=135
EDIT by VB: Moved into a seperate topic.