How do I prepare a wall for painting that hasn't been painted in 25 years?

I bought a house out of an estate and the interior hasn't had any work done to it in at least 25 yearsHow do I prepare a wall for painting that hasn't been painted in 25 years?
if the walls are not papered use a hot soapy solution of tsp it clean away grime, cig stains and preps the wall to be painted. directions are on the box.How do I prepare a wall for painting that hasn't been painted in 25 years?
Are you dealing with drywall? If so, remove any wallpaper (I find a steam cleaner to be the easist method) and prime the walls. I use Kilz2 because I have small children and the fumes aren't too bad. There is also a primer called Bin that works really well (better than Kilz) but it has strong fumes.

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