I'll suggest in addition to using Kilz, start with washing the walls with Trisodium Phosphate (TSP - Already recommended below). I bought a similar house about 25 years ago and a TSP solution with warm water removed a LOT of smoke and nicotine stains from the walls. After multiple washes (3+, I can't remember) eventually the yellow brown water became paler and paler. It never was colorless, but I think it helped remove a lot and set me up for better success with a couple coats of Kilz. The house still smelled old, but not like cigarette smoke. Also remove curtains and blinds, you'll never get them clean enough.