I've viewed several different threads and tried to piece things together but there is differing information everywhere including some of the applications mentioned in guides being outdated, and I'm not sure how to get around that as I am completely new to BDO modding... if anyone's generous enough to help, that would be much appreciated :)
Resorepless is outdated in the sense that it doesnt include the classes released after its last update. It is still a good starter point to get you started with modding and understanding how things work. There will be many more recent posts in that thread that are still valid.
The gamecommondata folder it will create to adjust character sliders (for the classes it supports) will still work but wont include all classes. It's best to download the most recent one (search for gamecommondata) to include all the classes. That folder is responsible for "crash on server selection" whern it's outdated.
Understand that resorepless will record the changes you select in the /.resorepless folder it will create. That folder gets recreated (its content erased) each time you run resorepless, so don't put your own files in that folder (like the instructions warn you about).
Create the folder structure (create a "/character" folder within /files_to_patch, etc.) to store your own mods and chose "keep the files" instead of "let the program decide" when you run meta injector to apply the mods.
Read up on the partcutgen tool to help you deal with the holes and clipping issues. There are posts containing the filenames of the outfits you're looking to fix (not all clothes).
I think there is also a video explaining the basics for modding BDO, the information should still be valid.
Remember that the game hasnt changed that much since its release. Most of the stuff you'll read will still be valid because they didnt rebuild the game from the ground up. Trial and error or more reading will help you weed out what doesnt work anymore (the old outfit names with a bunch of numbers for instance).
If you play on a server other than NA/EU, use the tool that bypasses the check preventing the mod from working. Additional steps will be required to "survive patch day" as well. every week, after each patch, you will have to reinstall the mods (if you dont want anything changed from your setup, just run meta injector AFTER it finished patching: launch the game, let it finish patching THEN run meta-injector)
When you come across a problem, start with a search in these forums (the looking glass icon on the top right corner will be your best friend). Every issue you can run into has already happened to someone and answers have been provided within these forums.
This should get you started :)
Have fun in your modding adventures :)