I've been decorating for what seems to be a lifetime now ... and I'm still not finished LoL ..
I had the walls professionally plastered as they were in Very bad condition but even then make sure that you go over any imperfections with some Quick Drying Filler and sanding block ... It makes a massive difference to the end result ...
I spent 3 days last week completing the front living room ... and that included painting the walls, ceiling and laying the laminate ... by day 3 I was ready to actually looking forward to being back at work ...