I am planning to paint my house but i don't know how to prepare a good surface before painting the walls. Please give me some ideas and suggestions?
I assume it's drywall. It's tough to advise without knowing the existing conditions, but you'd probably be safe with a primer. If it's a new wall that has not been painted, it depends if it's finished with drywall mud. If not, you'll need to mud the wall and sand it prior to applying primer.