Software
Is your Windows system properly setup for modding? Are your in-game settings appropriate for your computer, particularly your Graphics Settings?
Windows
Your Windows environment plays an important part in ensuring a stable modded game. PC Software such as video drivers should be up to date, particularly if you are experiencing texture issues like flickering, tearing, texture losses, or low FPS. DirectX and NET Framework versions can cause issues as well so keep them updated. In rare instances folder permissions can cause issues, so you might have to change the security settings.
Another possible source to check is your anti-virus software. One user solved a problem with the Rockstar Video Editor not saving clips, but only when Menyoo was loaded. On inspection it turned out that it was Windows Defender causing the issue. When Defender was temporarily disabled, the saving functionality was restored. This is unexpected, but it does happen.
In-Game Settings
When encountering crashes or visual issues, start by setting the in-game display and advanced graphic settings to default or lower if necessary - even if you exceed system requirements.
Game Version
Unless you are using a reverted/downgraded version of GTA 5, you should keep your game updated to ensure newer mods are compatible. Whether your GTA 5 Version is Steam, Epic, or Retail keeping it updated may solve some issues although updates invariably cause their own issues.
If you're using a warez and/or cracked version of GTA 5 don't expect these guides to help you. Cracked versions don't necessarily mod properly and are often infected with malware such as viruses and trojans.
Installations
Always use a Mods folder. Improper installation of mods, in the wrong folder or wrong path, or missing mod requirements are frequent causes of crashing. Caution is required for replace mods as they often involve more than one path/location. Automatic installers such as OIVs can replace new files with outdated ones. Avoid them if possible. OIVs are better installed manually, you unzip them.
Copying a new version of Update.rpf after a Rockstar game update, from the game folder to your mods folder, either manually or as prompted to do so by OpenIV will result in gameconfig.xml, dlclist.xml, and any of your customizations to be deleted and replaced, causing potential crashes and preventing addons from loading if you don't replace these files from backups.
Corrupt or missing game files may happen with or without meaningful error messages. The save game file may also be corrupted, particularly if autosaving during a crash. A verify integrity (or reinstall) will fix most issues, but not corrupt save files, so backup. If necessary start a new game.
Reinstalling
Doing a complete reinstall rather than a verify integrity is not usually necessary. Many users are under the wrong impression that this will fix broken mods as well. A reinstall only impacts GTA 5 files, it does nothing to your saved games or mod files. Which is why a clean reinstall is the way to go only when all else fails. This means uninstalling and then manually deleting any remaining files and folders in documents as if game never existed.
Game Updates
These are notorious for breaking games completely or specific mods. Remember that Rockstar updates and patches don't break GTA5, they only break modded GTA 5.