I would like to exchange a few nuggets of wisdom about publishing a game for Ludum Dare. There are a few things that I found out and there are many more things I probably don't know so let's share!
My main dev platform is GameMaker Studio and I like to publish in itch.io, so those are the areas with which I'll start. Feel free to expand to any other library/tool or platform.
So first of all, an absolute no-go is to export a game from GameMaker with an installer. I guess most people know that, since I haven't seen anyone do it in this LD yet, but in LD37 I came across a few. The reason this happens is probably because it's the default setting in GameMaker. Personally I think the option to export the game as a standalone package is not that obvious. It is hidden in the save dialog, down where any other tool lets you select a file type for saving.
So far, so obvious. But I learned somthing this Ludum Dare thanks to input from @negativice: If you export your GameMaker game as an exe, it will likely cause problems with people's virus scanners. When that happens, the game simply won't run, sometimes with no clear indication as to why. The reason is that when you export an exe, it is really a self-extracting zip-file, which some virus scanners find suspicious. The better way to publish the game is by exporting it to a regular zip file which will cause less problems.
Now about publishing on itch.io: There are a few things that I've seen again and again that are not really problematic but, let's say, mildly annoying. First of all, if you publish a Windows game, mark it as Windows-compatible when you upload it. If you don't do that, people who use the itch.io client will not be able to download your game, which can be a bit frustrating.
On the other hand, don't mark your source code as Windows-compatible, or the itch.io client will annoy the user with a popup asking them which version of the game they want to install. Yeah I know it's only one click and maybe you want the user to get your sources that way. But whatever you want, I think you should be aware of the mechanics in play here and decide accordingly.
So, is there any secret knowledge you would like to share? Unity? Pygame? Gamejolt? Google Drive? Github?
Finally I have a question for all the people publishing on different platforms (Linux, MacOS, Android, etc). Do you have a device for each and test extensively or do you just export, upload and hope for the best? Have you run into any compatibility issues (concretely with GameMaker) or does it usually work smoothly?