How do you get old old wallpaper off of walls or cover up tricks?

Steaming has always been my preferred method.

https://www.lowes.com/projects/paint-stain-and-wallpaper/remove-old-wallpaper/project

To cover you can use beadboard, paneling. If you want to paint, the wallpaper must come down first.

Peel as much as possible from the walls.

If you can't get to the backing, you may need to score the paper with a tool. Paper Tiger is easy to find. Light pressure because you don't want to damage the wall behind the paper.

Mix 50/50 fabric softener & warm water in a spray bottle or garden sprayer. I've read that vinegar is as effective but I have never used it.

Allow the mixture to sit for 5 - 10 minutes so that it saturates the adhesive on the paper backing.

Scrape with a plastic scraper.

Once it is all removed, wash the walls with warm soapy water (blue Dawn is my go-to) and a microfiber cloth.

Peel off the vinyl layer that has the pattern on it, get a spray bottle and fill it with as hot of water as you can get from the tap...mines about 130 degrees. Spray a 3x3 section really good....soak it for a few min...then start scraping with a plastic putty knife...it will come right off...IF you did a proper prime before you put it up..if you didnt....im sorry for you.

There is a tool called a paper tiger, which you roll around freehand on the wallpaper and it delivers mini-perforations into the wallpaper. Next, mix up some wallpaper paste remover, put it into a pressure sprayer, the type usually used to spray weeds, and spray the wall. saturate the paper, it will find its way into the perforations and loosen the bond. Wait about 20 minutes before trying to peel the wallpaper off the wall.

I dont understand "cover up tricks", is that something you are dealing with or something you want to do?

Alternative to the paper tiger method, you may be able to rent a wallpaper steamer. Hot, messy, but faster than the first method.